I always think it was unfair that Jonathan Linsley had to leave the show. I also think he could have been brought back into the show at virtually any time.
Somehow his character wasn't as annoying as it could have easily been.
He played a good, likeable part.
The interesting thing is his character was never actually written out of the show.
I'm not sure exactly how different he looked immediately after his crash diet, but I reckon there would have been a way round him continuing with the show.
I think some characters were unfairly dropped from the series. Mrs Avery showed some promise too.
Equally, I think some (later) characters should have been dropped from the series, but that's another topic!