the running numbers 2800-9. Five further orders were placed with Darlington Works between December 1928 and March 1935 for a further fifty-two locomotives to be delivered between August 1930 and June 1936. A final batch of eleven were ordered from Robert Stephenson and Company in February 1936 (works nos. 4124-34) for delivery between January and July 1937; resulting in a total of 73 B17s built. Sub-classes The first ten by the North British Locomotive Company were designated B17, later B17/1. The second and third batches had boilers supplied by Armstrong Whitworth and different springing and became B17/2. The next two batches had different springing and were designated B17/3. However, as the locomotives passed through the works the original springs were replaced by those of the later design and in 1937 the three sub-classes were merged into B17/1. The final Darlington batch introduced in 1936, and those built by Robert Stephenson and Company had , tenders and were intended for use in the North Eastern area of the LNER: these were designated B17/4. In September 1937 two locomotives (Nos. 2859 Norwich City and 2870 Tottenham Hotspur) were streamlined in the manner of the LNER Class A4s, renamed East Anglian and City of London and intended for use on the East Anglian train. They were designated B17/5. However, the streamlining was cladding for publicity purposes only and had little effect on the overall speed of the locomotive. By 1951 both engines had been stripped of the streamlining altogether. Between 1943 and 1957 most of the surviving members of the class were rebuilt with a LNER 100A boiler with increased pressure and were designated B17/6. Rebuilding Ten B17s were rebuilt by Edward Thompson as 2-cylinder locomotives with a LNER 100A boiler, between 1945 and 1949, becoming the Class B2. No more were rebuilt because of the success of the Thompson's B1 class. Accidents and incidents On 4 October 1929, locomotive No. 2808 Gunton was hauling an express passenger train which was in collision with a freight train at Tottenham, London after the latter had departed against a danger signal and subsequently stopped foul of a junction. On 15 February 1937, locomotive No. 2829 Narworth Castle was hauling a passenger train that was derailed at Sleaford North Junction, Lincolnshire due to excessive speed on a curve. Four people were killed and sixteen were injured, one seriously. On 10 February 1941, locomotive No. 2828 Harewood