Thanks guys. It is a 3 story property, and the fire started next door in the middle flat, where it was contained. It burnt the joists in the ceiling of that flat, but didn't go anywhere else. My windows were open, so obviously I came back to a house that smelt of smoke, but their justification seems to be that because the smoke got up into the top flat, and then into the loft space - even though it was just smoke, and no fire, they had to enter my place, and see if the smoke was up in my loft - which has been converted to a room, so is airtight. As I always have my windows on the latch for ventilation, that's how some smoke blew in.
I can understand some of the comments, but they knew the neighbour the other side of me had called me, and as they had enough time to put a ladder up the back to see if they could get in an open window next door to where the fire was, it wasn't a desperate situation, and they certainly had time to ring me before they broke in - I'd at least have told them to kick the back door in rather than the front one. I think they've reached a stage where they have impunity to do whatever they consider necessary, without thinking of the consequences, or even if it's the right thing to do.
And no, I've got an interlinked smoke alarm, and it wasn't going off, so again, what was their justification.
I'll get some onions tomorrow, then it'll be on to the air freshener