Sad news - decided to book an appointment with the vet today for Arthur, as he's been getting frailer the last couple of weeks and lost a lot of weight. I was prepared for the worst - 10 years old is very, very old for a bunny. Went to feed them all this morning, and he'd died in his sleep. Cried my eyes out, but feel better that 'nature took it's course'. RIP my brave bunny!