Hold onto your seat belt and Google 'vintage Supplies' on the world wide web thingy. Yours looks just like the CLR700. However, it is a repro item and you might just have to buy the whole unit at ÂŁ79.20 plus carriage. On the other hand they just may do the lense as a spare, you could always ask.
cheers
Bob
Just Googled CLR driving lamps and the same company do a replacement lense etc for ÂŁ37.20 plus carriage.
So brake open that piggy bank of yours and go for it!