Thanks, I phoned the vet and asked their advice and they asked me to take her in. They are confident that it is a tumour and as it is so big leave it alone providing she is happy in herself, is eating and none of the others are attacking her or the lump. I think she may be about 4 years old and she has will have a happy and peaceful time here, however long she manages to go on.
I will need more layers pellets the week after next if that's ok?