Or the test in Cheddar for that matter... Made sense as in those days there was a lot of nuclear concentrated in that area...
The Class 46 was a new one on me until your post and I thought I knew early 60s Diesels well... Clearly not...
Although, in my defence the Class 46 was very similar to the Class 45 and was still known as a 'Peak'..
The Wikipeda article on the '46 refers to the nuclear Flask test at Old Dalby...