There is a feliway diffuser you can buy that releases natural pheremones, similar to the ones from their mother. Its like a plug in air freshner.

I used it with our cats when we moved in. Had it on for a few weeks. and they settled in so easily, I was really surprised.

http://www.feliway.com/gb

Feliway really works when cats move into a new environment.
Did the cat in the sofa look like this btw?

Totally right on the milk front, it can really upset their tums.

Might be worth ordering one of these in or ask your vet if they have them.
http://www.tautiershop.ch/_1077
Really good for settling nervous pusses down,the plug ins have pheremones that are similar to what the mother cat has when she is feeding her babies. Calms frazzled nerves, there is also a spray version which you could put on blankets etc. In the short term you can get SOS drops from your chemist and put that on his belongings.

Hope he settles soon.

Darcy

Thanks everyone for the advice.

Last night was a fast improvement on the previous night. He kept himself hidden until mini-mimi went to bed (can't say I blame him) and then ate some treats from my hand. I picked him up to give him a little cuddle and then placed him on the sofa next to me. He stayed there all night between myself and my other half and adored the strokes and affection we gave him. He rewarded us with lots of purring and laid up as close as he could to us. He's such a soft ball of fluff that it's nigh on impossible to leave him alone when he's stretched out beside you

He also used his litter tray and judging by his food bowl this morning, he had a little bit of food during the night.

He didn't budge until we went to bed but was back under his trusty sofa this morning when I went to look in on him

Before and after:

YAY! See? It just takes time. Thanks for the pics! SO cute!

Oh he is such a cutie!