Interestingly, I did see a picture of a late 70s Raleigh with the extra brake bridge, but again the frame number format would be different. I also saw a picture of a Raleigh track bike from the 70s that had the wrap over seat stays, but that obviously had track dropouts.
Fruitbat, thanks for your suggestion
Have done some checking, and I don't think that it is a Carton, as the format of the frame number doesn't match, details obtained from http://www.carltoncycles.me.uk/details/dating.htm
Interestingly, I did see a picture of a late 70s Raleigh with the extra brake bridge, but again the frame number format would be different. I also saw a picture of a Raleigh track bike from the 70s that had the wrap over seat stays, but that obviously had track dropouts.