Thanks for everyone taking the time to comment. Your advice will really help me to get the piece just right
My wedding is this month so i'm trying to spend what time I can on this and other projects I have on the go, but I will try to update as soon as I have chance to work on it a bit more!
The height of the piece is something I would like to keep as it is, but I agree with increasing the lights and darks a little more.
@bharris Thanks for the nice comments. I think the cat needs reworking so I will probably find a nice pose for him 
@tombarrettillo The cat in a lap is a good idea. I will definitely try that out.
@IanS thanks Ian. Seconded on the cat, it never seemed right to me too.
@TessW Thanks Tess. I think the frame at the top was a happy accident. I might have to move it slightly though as it runs tangent with the line on the wallpaper. I want to try and further tell the story through the photos, without taking away the attention from the old guy.
@rcartwright Yeah I think the expression could be pushed a little more. I didn't want him to look too sad though, trying to go for a more subtle remembering the past expression
@Chip-Valecek That movie popped into my mind half way through working the piece. I might have to steal some color schemes from it 
@Art-Dud Do you mean "does" or "doesn't"? Were you thinking that I should make the upper part darker? I didn't want to create too much darkness at the top incase it distracts from the main subject, but I can see where you are coming from.
@Spencer-Hale Thanks Spencer. I will probably just rework the whole cat as it seems the weakest part of the piece 