Thanks for your replies, yes it s a pity I don't have another one although not quite sure what I would do with it if I did! I will keep a look out for the daffodil part of the mouthpiece at the next NVCF, although guess this part maybe quite hard to come by.
I think I have now identified the exact model:
http://www.britishtelephones.com/gec/k7842.htm