The 1948 Locomotive Exchange Trials were organised by the newly nationalised British Railways (BR). Locomotives from the former "Big Four" constituent companies (GWR, LMS, LNER, SR) were transferred to and worked on other regions. Officially, these comparisons were to identify the best qualities of the four different schools of thought of locomotive design so that they could be used in the planned BR standard designs. However, the testing had little scientific rigour, and political influence meant that LMS practice was largely followed by the new standard designs regardless. However, the trials were useful publicity for BR to show the unity of the new British Railways. To record the locomotive performances, one of three dynamometer cars were included in the consist directly behind the locomotive (with a GWR, LMS and NER version being available).
LMS engines operated over the Southern Region, where there were no water troughs, were paired with four-axled ex-WD tenders with larger water tanks. These were specially given LMS lettering for the occasion. Similarly, ex-Southern types used elsewhere, were paired with ex-LMS tenders with water scoops.
Locomotives used were as follows (NB numbers given should be the ones carried at the time, so this is a somewhat curious mixture of old pre-nationalisation numbers, prefixed numbers, and new BR numbers):
The four routes used were: LMS Euston to Carlisle, LNER Kings Cross to Leeds, GWR Paddington to Plymouth, and SR Waterloo to Exeter.
Official test runs on the LNER East Coast Main Line were held on the following dates, using the NER Dynamometer Car:
29 April, hauled by LMS Rebuilt Royal Scot Class 46162 Queens Westminster Rifleman in the down direction30 April, hauled by LMS Rebuilt Royal Scot Class 46162 Queens Westminster Rifleman in the up direction6 May, hauled by LMS Princess Coronation Class 46236 City of Bradford in the down direction7 May, hauled by LMS Princess Coronation Class 46236 City of Bradford in the up direction20 May, hauled by GWR King Class 6018 King Henry VI in the down direction21 May, hauled by GWR King Class 6018 King Henry VI in the up direction27 May, hauled by SR Merchant Navy Class 35017 Belgian Marine in the down direction28 May, hauled by SR Merchant Navy Class 35017 Belgian Marine in the up direction29 May, hauled by LMS Rebuilt Royal Scot Class 46162 Queens Westminster Rifleman in the down directionOfficial test runs on the LMS West Coast Main Line were held on the following dates, using the LMS Dynamometer Car whilst hauling The Royal Scot Express:
22 April, hauled by LMS Princess Coronation Class 46236 City of Bradford in the down direction23 April, hauled by LMS Princess Coronation Class 46236 City of Bradford in the up direction13 May, hauled by SR Merchant Navy Class 35017 Belgian Marine in the down direction14 May, hauled by SR Merchant Navy Class 35017 Belgian Marine in the up direction27 May, hauled by LNER Class A4 60034 Lord Faringdon in the down direction28 May, hauled by LNER Class A4 60034 Lord Faringdon in the up directionOfficial test runs on the SR West of England Main Line were held on the following dates, using the GWR Dynamometer Car whilst hauling the Atlantic Coast Express:
3 June, hauled by SR Merchant Navy Class 35018 British India Line in the down direction4 June, hauled by SR Merchant Navy Class 35018 British India Line in the up direction8 June, hauled by LNER Class A4 E22 Mallard in the down direction (loco declared failure at Exeter)10 June, hauled by LNER Class A4 60033 Seagull in the down direction11 June, hauled by LNER Class A4 60033 Seagull in the up direction17 June, hauled by LMS Rebuilt Royal Scot Class 46154 The Hussar in the down direction18 June, hauled by LMS Rebuilt Royal Scot Class 46154 The Hussar in the up direction24 June, hauled by LMS Princess Coronation Class 46236 City of Bradford in the down direction25 June, hauled by LMS Princess Coronation Class 46236 City of Bradford in the up directionOfficial test runs on the GWR Main Line were held on the following dates, using the GWR Dynamometer Car:
27 April, hauled by SR Merchant Navy Class 35019 French Line C.G.T in the down direction28 April, hauled by SR Merchant Navy Class 35019 French Line C.G.T in the up direction4 May, hauled by LNER Class A4 60033 Seagull in the down direction5 May, hauled by LNER Class A4 60033 Seagull in the up direction18 May, hauled by LMS Princess Coronation Class 46236 City of Bradford in the down direction19 May, hauled by LMS Princess Coronation Class 46236 City of Bradford in the up direction25 May, hauled by LMS Rebuilt Royal Scot Class 46162 Queens Westminster Rifleman in the down direction26 May, hauled by LMS Rebuilt Royal Scot Class 46162 Queens Westminster Rifleman in the up directionThe four routes used were: Midland Main Line St. Pancras to Manchester, Great Central Main Line Marylebone to Manchester, Highland Main Line Perth to Inverness, and South Devon Main Line Bristol to Plymouth.
Official test runs on the South Devon Main Line were held on the following dates, using the GWR Dynamometer Car:
7 July, hauled by LNER Class B1 61251 Oliver Bury in the up direction14 July, hauled by LMS Black Five 45253 in the up direction21 July, hauled by SR West Country class 34006 Bude in the up directionOfficial test runs on the Midland Main Line were held on the following dates, using the LMS Dynamometer Car:
1 June, hauled by LMS Black Five 45253 in the down direction4 June, hauled by LMS Black Five 45253 in the up direction15 June, hauled by LNER Class B1 61251 Oliver Bury in the down direction18 June, hauled by LNER Class B1 61251 Oliver Bury in the up direction22 June, hauled by SR West Country class 34005 Barnstaple in the down direction23 June, hauled by SR West Country class 34005 Barnstaple in the up directionOfficial test runs on the Great Central Main Line were held on the following dates, using the NER Dynamometer Car:
8 June, hauled by SR West Country class 34006 Bude in the down direction9 June, hauled by SR West Country class 34006 Bude in the up direction15 June, hauled by LMS Black Five 45253 in the down direction16 June, hauled by LMS Black Five 45253 in the up direction24 June, hauled by GWR Modified Hall Class 6990 Witherslack Hall in the down direction25 June, hauled by GWR Modified Hall Class 6990 Witherslack Hall in the up directionOfficial test runs on the Highland Main Line were held on the following dates, using the NER Dynamometer Car:
13 July, hauled by SR West Country class 34004 Yeovil in the down direction14 July, hauled by SR West Country class 34004 Yeovil in the up direction14 July, hauled by LMS Black Five 44799 in the down direction (on scheduled service, 1155am ex-Perth)20 July, hauled by LNER Class B1 61292 in the down direction21 July, hauled by LNER Class B1 61292 in the up directionThe four routes used were: London Midland Region Brent to Toton, Eastern Region Ferme Park (London) to New England (Peterborough), Western Region Acton (London) to Severn Tunnel Junction (South Wales), and Southern Region Bristol to Eastleigh. Due to the tests being held on non-public services, details are only available from the Official Report.
Eastern Region tests were carried out using the LMS Dynamometer Car by:
LNER Class O1 63773 on 27 JulyWD Austerity 2-10-0 73774 on 10 and 12 AugustLMS 8F class 48189 on 17 and 19 AugustGWR 2884 Class 3803 on 26 and 27 AugustLNER Class O7 63169 on 31 August and 2 SeptemberWestern Region tests were carried out using the NER Dynamometer Car by:
LMS 8F class 48189 on 28 and 30 JulyGWR 2884 Class 3803 on 10 and 12 AugustWD Austerity 2-10-0 73774 on 20 AugustWD Austerity 2-8-0 77000 on 27 AugustLNER Class O1 63773 on 31 August and 1 SeptemberLNER Class O7 63169Midland Region tests were carried out by:
LMS 8F class 48189 on 29 June and 2 JulyWD Austerity 2-10-0 73774 on 14 and 16 JulyLNER Class O1 63789 on 21 and 23 JulyLNER Class O7 63169 on 8 and 10 SeptemberGWR 2884 Class 3803Southern Region tests were carried out by:
WD Austerity 2-8-0 77000 on 10 and 12 AugustWD Austerity 2-10-0 73774 on 24 AugustLMS 8F class 48189 on 31 August and 2 SeptemberLNER Class O7 63169GWR 2884 Class 3803LNER Class O1 63773GWR 6990 Witherslack Hall - Great Central Railway (preserved).SR Merchant Navy class 35018 British India Line - West Coast Railway Co. (Carnforth)LNER A4 class 4468 Mallard - National Railway Museum,GWR 2884 Class 3803 - South Devon Railway,GWR Dynamometer Car No. 790 - South Devon Railway,LYR/LMS Dynamometer Car No. 45050 - Princess Royal Trust,NER Dynamometer Car No. 902502 - National Railway Museum.
