Welcome to the Clubman club . I have a blue one. Mine has the number stamped into the bottom bracket and is a 79 model.Had a very quick look at it but no sign of a frame number nothing on bottom bracket or seat post and can't see one on rear drop out either
Will there be one ????
Try mounting them vertically! That is what I am having to do now . I've got to fit 2 more in yet .