awwww bless he is probably scared at being away from familiar surroundings.
He should come round eventually. My parents rescued a feral cat a few years ago and she hid for at least 2 weeks.
It took a lot of patience and reassurance and it was a gradual process.
Sometimes they would get her out of her hiding place and stroke her until she felt relaxed and then let her go back to hide.
She is now a very loving cat but does not like strangers.
Maybe you could try Felliway Plug In to calm him down a bit?
Also try enticing him with treats like Pilchards, boiled white fish, tuna, chicken etc. And when he is eating it see if he will let you stroke him??
Also if he is feral - it might be an idea to get the vet to check him over. He could be uncomfortable or in pain also and it would help to get him checked.
Even if he has fleas that could be irritating him??
Hope that helps - there will be plenty more advice from the other forum members i expect.
Please keep us updated with the progress
