|In May 2011 Flying Scotsman was shown to the public in wartime black livery|
Now, according to an announcement this week by York Railway Museum, completion is further delayed and was now due by late spring 2012 due to the discovery of a number of additional defects.
Work is being carried out in Bury, Greater Manchester, and is "focusing on ensuring that the locomotive is in a condition to be able to run for decades to come", the museum said.
The work due to take place includes machining of the axle boxes and the repair and installation of the horn guides.
Steve Davies, director of NRM, said: "The Flying Scotsman restoration is one of the most complex steam locomotive engineering projects of its kind ever undertaken in Britain and there is no doubt that it has been challenging.
"There have been a number of points where unforeseen issues have arisen that have caused the project to be delayed whilst options were considered and decisions were made.
"These decisions were taken in accordance with our aims of ultimately maintaining maximum public exposure and enjoyment of the locomotive."
In 2004, the National Railway Museum bought Flying Scotsman for £2million. The appeal to keep No.4472 in Britain was supported by a £1.8 million grant from the National Heritage Memorial Fund and the generosity of the public.