Class 13 locomotives at Tinsley Yard in 1980

Here are two Class 13 locomotives I photographed at Tinsley in 1980,

Wikipedia explains:

The British Rail Class 13 was a type of diesel-electric shunting locomotive. The type was designed in 1965 because of the need to provide more powerful shunters for the Tinsley Marshalling Yard. 

Because of Tinsley's status as a hump yard, it was not possible to use a single locomotive owing to the risk of grounding. So, to achieve the required power, a pair of Class 08 shunters were permanently coupled in 'master and slave' formation, with the slave unit having had its cab removed. ... 

With the end of hump shunting at Tinsley the class became obsolete. The unique qualities of the locomotives were not required elsewhere and so withdrawal was inevitable; 13002 was withdrawn in 1983, with the remaining two locomotives going with the closure of Tinsley hump in 1985. None of this unusual class survives.