Okay it's a bit tricky for me, I think it would be fine without gift deed but you would have to provide the bank statements of the older bank account as well which will show cumulative build up of funds. But let others comment as well that's just my opinion.
As you said the money came from a joint account with father. Legally your father have 50 percent right on that money. You need gift deed to show that the transfer is done with full consent of your father and he has no right/claim left on that money and you can utilise that money for anything.