It sounds like an urban myth. The forward-facing guns of HMS Belfast are permanently positioned to score a direct hit on the London Gateway service station at Scratchwood.
It is no myth. The target is intentional. If the six-inch guns were loaded with shells, they could deliver an awesome pounding to the M1 cafe and toilet stop. Each shell weighs 112 pounds, similar to a sack of coal, and much more explosive. The forward guns could fire eight rounds per minute, meaning that Scratchwood could be obliterated in seconds.
But why this target in particular? It has nothing to do with the exorbitant price of its cappuccinos.
The imperilled service station sits neatly on the radius of the guns' comfortable range (about 18.5 km at 45º elevation, but the artillery could stretch to 23 km if pushed). A point anywhere within that band might have been chosen for the resting formation of the six forward guns. According to the ship's Chief Yeoman, Kevin Price, Scratchwood was picked on because it was a well-known landmark on the M1 motorway. "We could also hit Cheshunt, or Gidea Park, or fall just shy of Dartford," he tells us. Scratchwood, though, has a certain quotidian monotony that invites comparison with Betjeman's "come friendly bombs" prejudice.
The targeting was decided as long ago as 1971. This was the year HMS Belfast was first moored in the Pool of London to serve as a museum ship, following decades of distinguished service as one of the Royal Navy's most powerful light cruisers. It goes without saying that the Belfast would never have cause to bombard the motorway — but the guns had to point somewhere, and targeting a famously humdrum location could only help with press and popular attention.
The other guns on the ship have not been so deliberately targeted, and are often swivelled. The numerous four-inch guns along the vessel's sides would probably hit surrounding buildings, making short work of the More London complex. If they could clear the skyline, they'd have a maximum range of about 18 km. This is precisely the distance to Sutton town centre.
HMS Belfast is operated by Imperial War Museum and is open daily to the public.