I am guessing that this was a B Movie. It runs for only 1 hour and 15 minutes and takes place mostly inside four rooms and a staircase. Nevertheless, it is worth a watch if for no other reason than the comedy turn by Wally Patch as the lighthouse keeper [pictured] kept me chuckling.
Anyway, this is a spy thriller made and set during the Second World War. It begins in the HQ of the British spy network in London. The chief spymaster gets a coded message that a top German spy is on a ship steaming from Ireland to Portugal taking with him/her [nobody knows if this spy is a man or woman] top secret plans to something or another vital to the war effort. Bad news. But good news - a crack British spy is also on board and seeking to identify the spy and get the stuff back again. We then go to the ship to meet the six passengers. A right mixed bunch they are too. All very shifty and suspicious. The ship is then torpedoed - or so we are told clearly the budget wasn't up to special effects like that - and the passengers fetch up in a lifeboat. It is foggy and the British destroyer that rescues the crew cannot find them. They are, however, found by the captain of the U-boat - now sunk by the destroyer. He is the 7th survivor, you see. The lifeboat ends up at a lighthouse, manned by the comedy actor Patch and his comic sidekick. The rest of the film is taken up by the passengers trying to work out who the spy is before the replacement U-boat arrives to take them all into captivity as prisoners of war.
Apart from Patch, I recognised a few faces from other films but I can't say that I actually knew any of them. The acting was pretty good, considering, and the script kept darting around with plenty of red herrings to keep the viewer guessing. Everyone has a dark secret to hide - conman, dodgy business deals and so forth.
The most obvious thing that struck me was the absolute absence of any music. Apart from a few seconds of tune over the opening credits, there was nothing. No incidental music and not much in the way of sound effects. It was almost as if they went to a theatre, set up a couple of cameras and filmed a stage show. The lack of exterior shots was rather offputting. Apart from the lifeboat shot - which was so tightly cropped that it could have been shot on a duckpond - we are either inside the ship or inside the lighthouse.
It helped to pass the time during covid lockdown, but unless you are a big fan of Wally Patch and his comic antics, I'm not sure I would bother. Still, it is available to view HERE if you are interested in a period piece.