Broadly, initial allocations of classes eventually seen in Cornwall were:
1956 Cl 101 for NER, LMR and ScR - some migrated to WR (3-car sets 800-6), including Laira 1974-5 and 1987-97.
1957 Cl 103 for Walsall - 2 x 2-car sets (P200-1) migrated to Kingswear for the 1972 season.
1958 Cl 108 for ER and LMR - some migrated to ScR and WR, including Laira 1987-92.
1957 Cl 116 for Tyseley (1957), Cathays (1957-8) and Marsh Junction (1958) suburban.
1959 Cl 117 for Reading and Southall suburban, mainline local and branches.
1960 Cl 118 for Laira and Marsh Junction suburban, mainline local, and branches.
1958 Cl 119 for Marsh Junction (1958), Canton (1959) and Tyseley (1960) cross-country.
1958 Cl 120 for Canton and Marsh Junction (1958), ScR (1959-60) and Tyseley (1961) cross-country.
1960 Cl 121 for Southall, Reading and Marsh Junction branches.
1958 Cl 122 for Southall, Reading and Tyseley branches.
1958 AC Cars - 1 at Perth for Crieff and 4 at Swindon for Kemble.
1963 Cl 123 for Canton - migrated to Reading in 1968 and operated on summer Saturday Paddington to Minehead services. There was also a Fulham to Argyle Footex in 1971 but did they ever reach Cornwall?
After the 1955 Modernisation Plan orders had been placed but before delivery many local services and branches had been closed, and closures continued into the 1970s. Reallocations started almost immediately and many units were never used on the services for which they’d been intended. Eg Cl 123 were built for a Cardiff-Brighton service but didn't run east of Portsmouth.
Initially the vehicles within a set were fairly stable with Laira sets having an LA-prefix set number. By 1971 Plymouth sets had received a P-prefix set number, but from the mid-60s WR non-gangwayed sets were being gangwayed for paytrain operation, then refurbished and painted blue. These were not done in sequence and many sets were reformed apparently randomly with sometimes driving cars and trailers from two or three different classes. In other cases, non-gangwayed cars were paired with gangwayed cars having a lavatory, while yet again sometimes extra power-cars were added so that units could keep up with modern schedules.
Some of the Modernisation Plan DMUs had a 40-year lifespan, so were generally more successful than their locomotive counterparts some of which lasted only 10 years in traffic. Sadly these early vehicles were either withdrawn before the preservation movement took off, or were not seen as glamorous, and therefore many classes became extinct fairly early on.
DMU Allocations to Devon & Cornwall 1960-1997
There can be some discrepancy between vehicles officially allocated and wheels on the ground, due to lag in documentation and temporary loans in or out which are not always recorded. There is also conflicting evidence whether the 2 x AC Cars were officially allocated to St Blazey or merely outbased from Laira.
It may also be seen that there is excessive churn of classes in and out as BR tries to optimise efficiency around the regions. For example, why did they move Cl 101 to Laira in 1974 and then immediately reverse that decision in 1975?
Apr to Jul 1960 - 15 x 3-car Cl 118 delivered, 13 sets officially allocated to Laira, new depot created at Belmont and Harwell Street, to operate west of Newton Abbot, plus 2 sets allocated to Marsh Junction for the Bristol - Taunton service. Similar in design to Cl 116 and 117 suburban units, the Cl 117 and 118 trailer-composites had lavatories for mainline use albeit still non-gangwayed.
13th Jun 60 - Plymouth to Saltash auto-trains converted to DMU (except Tavistock inter-workings).
Jun 61 - 8 x Cl 122 (LA 100-7) arrive at Laira.
Jun 62 - Most Cl 118 replaced by Cl 116 and 120; also 1 x Cl 121 reached Falmouth.
1963 - Laira DMU fleet pretty stable.
1964 - More Cl 116 and 120 arrive, plus 2 x Cl 121, and 2 x AC Cars for Yeovil plus 2 at St Blazey for Bodmin.
5th Oct 64 - most remaining main line local stations close.
1965 - More Cl 116 and 121 arrive, while some Cl 118 return to the area. Fleet size peaks at 130 vehicles.
1966 - Cl 116 start to depart. 2 x AC Cars leave Yeovil.
1967 - General reduction. 2 x AC Cars leave Bodmin.
1968 - Further reduction but some Cl 117 arrive and most Cl 122 leave.
1969 - Slight reduction.
Oct 69 - Belmont and Harwell Street closed and servicing transferred to Laira.
1970 - Slight reduction. Fleet size stabilises at around 54 vehicles.
1971 - 6 x Cl 119 arrive, all Cl 117 and most Cl 118 depart.
1972 - Cl 103 arrive and depart.
1973 - Fleet is now mainly Cl 119 with a few Cl 116, 118, 120, 121 and 122.
1974 - 5 x 3-car Cl 101 displace several Cl 119 and 120.
1975 - 5 x Cl 101 replaced by several Cl 119 and 120.
1976 - Several Cl 119 replaced by Cl 118. Cl 116 and 122 depart, fleet size reduced to 42 vehicles.
1977 - Last Cl 119 depart. Fleet is now all Cl 118 and 120, plus 3 x Cl 121.
1978 - 2 x Cl 116 displace some Cl 120.
1979 - Little change.
1980 - Cl 117 and a few Cl 119 return to the area, last Cl 120 depart.
1981 - Cl 119 depart.
1982 - Cl 117 depart, now almost all Cl 118.
1983 - Last Cl 116 depart, now all Cl 118 plus 1 x Cl 121.
1984 - No change.
1985 - Little change.
1986 - Drastic reduction to 4 x Cl 118, fleet size now 11 vehicles.
1987 - Cl 101, 108, 117, 118, 121 and 122 arrive to replace Cl 142. Fleet size now 50 vehicles.
1988 - Cl 117 depart.
1989 - Cl 118 depart.
1990 - More Cl 101 and 108 arrive. Fleet size peaks at 60 vehicles.
1991 - Little change.
1992 - Cl 108 and 121 and most 101 depart. Fleet size reduced to 9 vehicles.
1993 - 1 x Cl 101 plus 5 x Cl 122 remain, while 4 x Cl 117 return to the area.
24th May 94 - 1 x Cl 101 plus 4 x Cl 117 transferred from Laira to Penzance.
1995 - 1 x Cl 117 added temporarily for the summer season, then 1 x Cl 117 withdrawn.
Jul 95 - Last Cl 119 in service moved to Penzance but not used, so sent for scrap on 11th Aug.
1996 - No change.
Mar 1997 - Remaining cars reallocated from Penzance to Headquarters and moved to store at Exeter.
Just to remind you John invites any additional information you may have.
Kind regards, Peter