From the website....
Locomotion Models are delighted to announce that they have commissioned a OO Scale Class 33/1 locomotive No. D6535 ‘Hertfordshire Rail Tours’ from Heljan.
This is the first exclusive edition model produced for Locomotion Models by the Danish manufacturer.
Built by the Birmingham Railway Carriage & Wagon Company it was delivered on the 10th December 1960, it entered service on British Railways Southern Region as D6535.
It was renumbered 33116 on 31st December 1973 and was named ‘Hertfordshire Rail Tours’ on 11th December 1993 at Weymouth station by John Farrow and Ian Kapur of Hertfordshire Rail Tours. The name was carried until April 1998.
It was withdrawn from traffic in August 1998 and stored out of use at Old Oak Common until June 2003 when it was acquired for the National Collection.
D6535 was push/pull fitted and was usually found operating with non-powered 4TC units on non electrified lines on the Southern Region. These were designated as Class 33/1 locomotives for push/pull working which was commonplace between Bournemouth and Weymouth prior to completion of the Weymouth electrification scheme in 1988.
The National Railway Museum loaned D6535 to the Great Central Railway in April 2005 where it has been located ever since and where it is available for traffic.