Air of Authority - A History of RAF Organisation

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226 - 235 Operational Conversion Units


226 Operational Conversion Unit

This was formed at Molesworth in No 11 Group on 15 August 1946 from No 1335 Conversion Unit to train fighter pilots.  It was equipped with a variety of types including Tempests, Hornets, Meteors and Vampires.  It moved to Bentwaters on 10 October 1946 and then to Driffield on 26 August 1949, where it was transferred to No 21 Group and it disbanded by being redesignated No 203 Advanced Flying School on 31 August 1949.

It was reformed on 1 September 1949 in No 12 Group by renaming No 203 AFS at Stradishall to train Meteor pilots.  On 15 December 1950, its Vampire Flight moved to Leuchars to form No 229 OCU and on 18 February 1952 it was transferred to No 81 Group but by the time it disbanded on 3 June 1955 it had been transferred to No 11 Group .

It reformed again, this time by redesignating the Lightning Conversion Squadron at Middleton St George on 1 June 1963.  It moved to Coltishall on 20 April 1964, where it disbanded on 30 September 1974.

It reformed the following day by redesignating the Jaguar Conversion Unit at Lossiemouth and was disbanded by being redesignated No 16 (Reserve) Squadron on 1 November 1991.  

 Shadow/Reserve Squadron designations: -

Squadron From To
No 145 1 Jun 1963 13 Apr 1964
No 65 1 Sep 1970 17 Jun 1974

Codes used: -

BB, KD, XL 1948 – 1949
HX, KR, TO, UU 1948 - 1951

Aircraft & Markings


227 Operational Conversion Unit

This was formed in No 12 Group at Andover by renaming No 43 OTU on 7 May 1947 to train aircrew for AOP squadrons.  It was redesignated No 227 (AOP) OCU on 1 December 1947 and moved to Middle Wallop between 26-30 January 1948.  It disbanded on being amalgamated with No 22 EFTS and renamed The Air Observation Post School on 1 May 1950.

Codes used: -  

BD, PF 1947 - 1950

Aircraft & Markings 


228 Operational Conversion Unit

This was formed in No 12 Group at Leeming from No 13 and 54 OTUs on 1 May 1947.  Tasked with tactical light bomber and night fighter crews, it was equipped with Mosquito’s, Meteors and later Javelins, with which it began all-weather fighter training.  It was transferred to No 81 Group on  22 February 1952  and on 17 April 1956 it moved the North Luffenham due to Leeming being rebuilt, returning on 25 January 1957.  With the disbandment of No 81 Group it was transferred to No 11 Group on 23 March 1958 and disbanded at Leeming on 15 September 1961.

It reformed in No 11 Sector at Leuchars on 1 May 1965, tasked with training Javelin crews for overseas operations and disbanded on 23 December 1966.

It reformed again, this time at Coningsby on 1 August 1968 to train Phantom crews.  From 1 March to 1 November 1984 it moved to Waddington, whilst runway resurfacing was carried out at Coningsby.  It moved Leuchars on 6 April 1987 and disbanded on 31 March 1991.  

Shadow/Reserve Squadron designations: -

Squadron   From   To  
No 137   11 Jan 1956   15 Sep 1961  
No 11   11 Jan 1966   23 Dec 1966  
No 64 (R)   16 May 1968   31 Jan 1991  

Aircraft & Markings


229 Operational Conversion Unit

This was formed at Leuchars from the Vampire Flight of No 226 OCU on 15 December 1950 to train fighter pilots, later operating Sabres and then Hunters. It moved to Chivenor on 28 March 1951 and on 20 February 1952 was transferred to No 81 Group until this disbanded, when it was transferred to No 11 Group on 22 March 1958.  On 2 September 1974 it moved to Brawdy , where it was effectively disbanded by being renamed Tactical Weapons Unit. 

It reformed at Coningsby in No 11 Group on 1 November 1984 to train crews in the air defence role on the Tornado F Mk 2 and 3.  It was disbanded by being redesignated No 56 (Reserve) Squadron on 1 July 1992.  

Shadow/Reserve Squadron designations: -

Squadron   From   To  
No 127   11 Jan 1956   22 Oct 1958  
No 234   22 Oct 1958   2 Sep 1974  
No 131  15 Mar 1958 22 Oct 1958  
No 145   22 Oct 1958  1 Jun 1963  
No 63   1 Jun 1963   2 Sep 1974  
No 79   2 Jan 1967  2 Sep 1974  
No 65 (R)   31 Dec 1986   30 Jun 1992  

Codes used: -

ES, RS 1950 - 1959

 Aircraft & Markings

230 Operational Conversion Unit

This was formed at Lindholme by renaming No 1653 Conversion Unit on 15 March 1947, equipped with Lancasters.  It moved to Scampton on 21 February 1949 where it re-equipped with Lincolns, disbanding on 15 October 1952 with the the remnants becoming the Reserve Training Squadron.

It was reformed at Upwood on 1 August 1953 by renaming the Lincoln Conversion Flight but disbanded on 1 February 1955 and reverted to its previous title. 

It reformed again, this time at Waddington on 31 May 1956 in No 1 Group to train Vulcan crews.  It moved to Finningley on 18 June 1961 and on 8 December 1969 to Scampton, where it disbanded on 31 August 1981.  

Codes used: -

YW, A3   1948 - 1949
SN   1949 - 1951

 Aircraft & Markings

231 Operational Conversion Unit

This formed at Coningsby from a nucleus provided by No 16 OTU on 15 March 1947 to train light bomber and PR crews on the Mosquito.  Disbanded on 4 December 1949.

It reformed at Bassingbourn in No 1 Group to train Canberra crews on 1 December 1951, absorbing No 237 OCU and No 204 AFS as 'D' Squadron on 29 February 1952.  'D' Squadron was disestablished on 26 June 1955 and 'C' (PR) Squadron was detached to Merryfield in April 1955, to Weston Zoyland on 26 June, then back to Merryfield on 1 October, where it remained until 23 October 1956 when it was redesignated No 237 OCU at Wyton but the PR training task reverted to No 231 OCU on 21 January 1958.  On 19 May 1969 it moved to Cottesmore, to Marham on 12 February 1976 then to Wyton in No 18 Group on 30 July 1982, remaining there until disbanding on 15 December 1990 when it was redesignated Canberra Standardisation Training Flight.

The CSTF was reverted to being No 231 OCU on 13 May 1991, again at Wyton but was disbanded  on 23 April 1993.  

Aircraft & Markings


 232 Operational Conversion Unit

This was formed at Gaydon in No 3 Group on 21 February 1955 to train Valiant crews and from 28 November 1957 crews for the Victor.  'C' Squadron was formed on 1 November 1961 and moved to Cottesmore to conduct the training of Victor crews, and this was redesignated Victor Training Flight on 1 April 1962.  It disbanded on 30 June 1965 and the Tanker Training Flight was formed at Marham.

 It reformed at Marham in No 1 Group by redesignating the Victor OCU at Marham and the Victor Training Flight at Wittering on 6 June 1970, being disbanded on 4 April 1986 as the result of the withdrawal of the Victor from service.  


 Aircraft & Markings


 233 Operational Conversion Unit

No 233 OCU originally formed on 1 September 1952 at RAF Pembrey, near Kidwelly, South Wales, and the unit’s Badge, approved in September 1953, depicted the head of a Welsh Wild-Cat, the motto ‘YMLAEN’, meaning ‘Forward’ in Welsh  This badge was the only marking worn by the unit’s aircraft, and was positioned just below the front quarter-light of the cockpit of its Vampires.   The role of the OCU was to train Vampire ground attack pilots, and later, Hunter day fighter pilots.  The Station Commander was also the Officer Commanding the OCU.  The OC Flying Wing was the Chief Instructor.  The Station badge at that time was the No 233 OCU, which was adorned on all the RAF Pembrey Station vehicles


The aircraft operated by the OCU were:


Vampire FB5  - September 1952 - 1956

Vampire FB9     ?

Hunter F1       - December 1955 - September 1957


Support aircraft


Tempest TT5   - February 1955 to June 1955

Vampire T11   - February 1953 to ?

Meteor T7       - September 1952 to February 1953

Meteor F8       - Late 1956 to September 1957

Balliol T2            ?

Tiger Moth T2    ?

Oxford T1          ?

Mosquito T3       ? 

Mosquito TT35 - June 1955 to late 1956 

Chipmunk T10    ?


The OCU disbanded on 1 September 1957.


No 233 OCU re-formed at RAF Wittering on 1 October 1970 by renaming the Harrier Conversion Unit, the Harrier Operational Conversion Unit, initially marking the Harriers with a yellow grasshopper with the words ‘Harrier Operational Conversion Unit’ markings in white, positioned on the lower side of the nose of its Harrier GR1s.  On 3 August 1973, the CO unveiled the new OCU markings, and from May 1974 they slowly began to replace the earlier markings on the lower side of the noses of its Harriers 1As.  These markings were the head of a Welsh Wild-Cat on a pale Blue disc, with two coloured bars on either side, coloured Red/Grey & Yellow/Black and outlined in pale Blue.  These colours represented the then four operational Harrier squadrons.  Red for No 1(F) Squadron, Yellow for No 3(F) Squadron, Black for No IV(AC) Squadron and Dark Sea Grey for No 20 Squadron.  The OCU subsequently operated updated T2/2A, GR3 and T4/4A versions of the Harrier. 


The role of the unit was to not only train new pilots to fly the Harrier, but also train Harrier Qualified Flying Instructors, Qualified Weapons Instructors, Electronic Warfare Instructors, Instrument Rating Examiners, and short courses for Test Pilots from Boscombe Down, Senior Officer Aquaint Courses and Refresher courses.  The unit also provided the Harrier Examiners on behalf of the CFS, who conducted the annual evaluation of the front line Harrier squadron pilots.  The OCU comprised two Flights, 'A' (Advanced) Flight being staffed by QFIs, and 'B' (Basic) Flight by QFIs, although some instructors had dual qualifications.  


The Harrier GR5 Conversion Team (GR5CT) was formed within 233 OCU, and three pilots detached to the USMCAS at Cherry Point, North Carolina, to convert onto the AV-8B Harrier II, prior to delivery of the first new Harrier GR5 to Wittering.  On 30 March 1988, the first ‘in-service’ flight took place of a GR5 from Wittering, a date which effectively marked the commencement of short conversion courses for the remaining OCU instructors and then initially 1(F) Sqn pilots.  The first GR5 Long Course commenced in July 1989


Because there were no two-seat versions of the Harrier GR5, the OCU continued to use GR3 and T4/4A Harriers for the initial phase of the Harrier II conversion courses.  The markings carried on the GR5s remained the same as the earlier marks of the units aircraft.  The only difference was that the GR5s were painted overall in the NATO Green upper/Medium Green lower colour scheme.  


On 1 September 1992, the Harrier OCU was re-designated No 20(R) Squadron.  The aircraft operated by the unit were:


Harrier GR1            - 1 October 1970 to 1973

Harrier GR1A         - 1971 to 1975

Harrier T2               - July 1970 to 1973

Harrier T2A            -  1973 to 1976 

Harrier GR3            - 1973 to 31August 1992

Harrier T4 & 4A     -  1973 to 31 August 1992

Harrier GR5            - 29 May 1987 to 31 August 1992


Aircraft fin codes
GR1 to GR3
1969 -74 - The last two numbers of the serial number in RED
1974 - 76 - Two numbers (not the serial number) in PALE BLUE
1977 - 83 - Single PALE BLUE Letter
1984 - 88 - Single WHITE letter
1989 - 1992 - WHITE '3' + WHITE Letter 
1988 - 1990 - Single WHITE letter
1990 - 1992 - WHITE '5' + WHITE Letter 


Officers Commanding


Gp Capt T B Beresford                            1 Sep 1952
Gp Capt W T F Wightman                       11 Aug 1954
Gp Capt W A Toyne                               26 Nov 1956 to 1 Sep 1957 (233 OCU disbanded.)

Wg Cdr L A B Baker                              1 Oct 1970

Wg Cdr P King                                       1 Aug 1972

Wg Cdr R M Austin AFC                       14 Jun 1974

Wg Cdr J D Rust                                   24 Jun 1977

Wg Cdr P Millar                                    22 Oct 1979

Wg Cdr A J Chaplin                               12 Jul 1982

Wg Cdr S G Jennings                             18 May 1984

Wg Cdr P W Day                                  19 Dec 1986

Wg Cdr P A Robinson                             9 Jun 1989

Wg Cdr T A Harper                               20 Mar 1992 - 31 Aug 1992

Shadow/Reserve Squadron designations: -

Squadron   From   To  
No 129  11 Jan 1956   1 Sep 1957 

My thanks to Norman Roberson for this detailed description of No 233 OCU.

Aircraft & Markings


235 Operational Conversion Unit

This was formed at Calshot from No 4 OTU to train flying boat crews on 31 July 1947, equipped with Sunderlands, it was disbanded on 17 October 1953, its tasking being taken over by the Flying Boat Training Squadron at Pembroke Dock.

Codes used: -  

TA 1947 - 1951
D 1951 - 1953

Aircraft & Markings

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