Hello Annie - As edh6 revealed in my thread, in 1942 the L.N.E.R. N.E. Area was short of motive power and requested a loan of engines. The Southern Railway offered Lord Nelsons but the L.N.E.R. declined the four-cylinder locos on grounds of maintenance concerns. In October 1942 ten N15 Class King Arthur 4-6-0s went north to Heaton shed at Newcastle. Ed reported that they were all from the LSWR built batch. They worked from Heaton along the ECML to Edinburgh on a regular basis but in July 1943 returned to the Southern after the USATC S160 Class 2-8-0s became available.
Regarding the S160: - The RCTS describes them as U.S. Army Class S160 4ft 9in Engines. Between March 1943 and January 1944 168 were acquired by the L.N.E.R. and remained on loan until after D-Day in June 1944. The L.N.E.R. returned all but one to the US Army between August and September 1944. No. 1707 was damaged during August 1944, went in to works in January 1945 and sent on to Europe after VE Day in May 1945.
Another foreign engine on loan to the L.N.E.R. was the Class O6 2-8-0, better known as the Stanier 8F. The L.N.E.R. orderd 68 in March 1943 with 25 from Brighton works and 43 from Darlington. The Brighton works engines arrived first, from September 1944. At first they were classed as "WD" but gained O6 in September 1945 when the first Darlington engine appeared. Some of the Darlington order, 20 locos was switched to Doncaster. in February 1944. The Darlington and Doncaster engines were all delivered by 1946. The classification O6 was discontinued in 1947 with the transfer of all the locos to the L.M.S.
The Classification O7 was the designation for the Ministry of Supply Riddles Austerity Class 4ft 8 1/2in Engines. The L.N.E.R. had 350 on loan from the MoS by March 1944. all in use while waiting on transfer overseas. 63 went to the GWR in August and September 1944 to assist them after losing their loan USATC S160s. By November a further 80 were transferred to the GWR and 23 went to the SR. The remainder were out of operating stock by February 1945, overhauled and sent to the continent. After WWII, in November 1945 the L.N.E.R. agreed to take 190 on loan from the government, almost all of which had been in use in Europe but were then in store. In November 1946 the L.N.E.R. decided tp purchase 200 "Austerities" for £4,500 each. The 190 on loan were transferred from operating stock to running stock. The remaining ten arrived in January 1947 when the classification O7 was introduced. All numbered 3000-3199. A further 210 were then agreed to be taken on loan, increasing to 278 in September. Not all of these were in operating condition and several were used as parts donors to engines requiring lesser repairs while awaiting overhaul. It took until July 1948 to put the last of them in to service.During December 1948 the BTC bought an additional 533 Austerities and the classification O7 was discontinued in January 1949, changing to WD 2-8-0. Some 733 engines were on Eastern Region and North East Region books It took until 1959 for the two regions to operate independent book stocks.
I almost didn't recognize that little N10 with that smart GER paintwork and dashing little sideplates!! 
