Only one car had an early withdrawal, DMBS 51170 in May '71.
When the line out of Kings Cross was electrified the Class was withdrawn as non-standard and redundant. Withdrawal dates were between Oct '76 and Feb '77. Many of the class were cut up at Doncaster Works and Booth Roe Metals, Rotherham.
Some cars spent some time in storage at March, as seen in these four pictures below taken by Robert White.
The final image shows 51172 sitting in front of 59453 & 51159 at Swindon Works on the 19th January 1978. The loco is 24 052. Neil Cannon.