Pretty much nothing I like about that combo. The jacket could be nice, but it looks tight and short. I would also pair it with mid grey trousers, not tan/brown. The shirt has a little too much going on it in for the texture of the jacket, imo. I think a bengal striped ocdb, or a plain pale blue ocbd would look nicer with the jacket. Also, I would opt for a cream puff stuffed a bit further into the pocket.
Thanks for the feedback.
I do need to get the jacket taken out a little, well spotted. The length doesn't bother me, nor does the pairing with light-coloured trousers - although I'll try the jacket out with a mid shade trouser when such comes to hand. (I'm travelling.)
Might be difficult to see from the photo, but the dark blue square actually picks up the tertiary colour in the shirt. I'd be worried that a cream PS might be too contrasty and distracting..