The British Rail built class 27 also known as BRCW Type 2 during 1961-1962.
69 Locos were ordered and Birmingham Railway Carriage and Wagon Company in Smethwick (BRCW), were awarded the contract.
BRCW had primarily constructed Diesel Multiple Units for rural passenger services previously and in this instance this was a unique operation in loco building as BRCW went into a partnership arrangement with Swiss Company Sulzer Brothers of Winterthur, they had constructed a dozen locos for CIE in Southern Ireland previously in 1956-57.
The Sulzer 6LDA with four GEC Traction Motors was deemed a suitable power unit for these successful engines, this was rated at 1250hp and the locos were able to travel at speeds up to 90 MPH.
Locos were delivered using the following number scheme D5347-D5415.
They were constructed with Steam Heat Boilers, to enable them to work Passenger Trains, although as with Class 26 they were a Mixed Traffic Loco.
D5347-5369 were allocated from new to Eastfield (Glasgow) D5370-D5378 to Thornaby on Teesside and D5379-D5415 to Cricklewood North London, they could be found on a variety of passenger and Freight and Parcel Workings.
Leicester gained an allocation from late Summer 1963 and the Thornaby engines were to be transferred down to Leicester, regular workings would see them reach Peterborough via what is now the Nene Valley Railway and the closed route to Northampton.
The remaining Cricklewood and The Leicester allocation were transferred to Scotland by the end of 1969.
The regular haunts for the class were on the West Highland Line out of Glasgow Queen Street working to Oban, Fort William and Mallaig where they would work until the late 1970s/early 1980s when surplus class 37 locos were transferred to Scotland.
One unusual innovation which involved 24 class members was the decision to replace unreliable DMU’s on the Edinburgh-Glasgow run with what was an unconventional in BR operating practice decision to run the train with more modern coaches and a loco working on either end in push pull operation.
The 24 locos chosen were 27/1 which retained a boiler and 27/2 which had a supplementary Electric Train Heating Generator the locos numbered 27101-112 and 201-212 were to be worked intensively and became unreliable with a number of failures and even loco fires being a regular occurrence.
These workings were to last from 1971-1980, before replacement by class 47s and more modern coaching stock yet again.
The class was to run in BR service from 1961 to 1987 with regular duties on Edinburgh-Dundee passenger workings being amongst the last duties they were booked.
Farewell passenger trains were organised and one pair reached York and three had a final run to Inverness on passenger trains.
Eight locos were preserved and of these 5 are currently operable.