The first couple of times I tried this bit – it drove me

I must have used every bit of ammo i had trying to blow everything in the room up looking for an exit.

In the end i found the exit by accident (i was wondering around and dropped through the floor!).

OK - When you have cleared the room of bad guys, make your way to the back of the room (towards the right i think). Just have a look around on the floor and you will notice some boards on the floor (a patch of the floor will look different from the rest of the floor). Simply blow this bit of floor away and it will reveal the exit.

If you have taken care of the bad guys by lobbing grenades everywhere the chances are you may have already removed the covering and so all you have to do is look for the hole.

Just have a wander around looking at the floor and you shouldn't be spending too much time on this stage