The Sea Dart launcher is on the Foc'sle, this looks like its coming from midships. Granted it looks like a sea dart launch plenty of smoke and sh&*e. Just looks odd, unless she was steaming at high speed for the launch.
Given the height of the weapon I'd say it's likely that it is the dart and the ship has just steamed through the launch point, hence the residual cloud sitting where it is. The only launchers around there are decoys, and it's not one of them.
It's also, as S_S says above, about the only device on board capable of generating that amount of smoke.
I remember watching a live launch on the Invincible in 94/95 ish, everyone was stood on the flight deck, cameras poised, the PWO is counting down over the main broadcast 3, 2, 1 BANG off it went, everyone got a lovley pic of a huge plume of smoke, the only decent pic was the phot department and that was only cos they were shooting with a cine camera. Impressive sight
Guys fired 16 in my time fcuking great experience and a definate penis extension its a Dart 40 miles at mach 2.5 the boost motor just about to come off, 60s technology though. tried a shot at exocet once no fcuking chance mssed by miles thats why the plume is heading off to the stars its all in the flight profile. 42s sleek grey messengers of death - in their time. Manchester was the dogs knob everything worked even had a bash at a yank target on Global 86 it was doing mach 2 locked him up "Birds afirm" but the fecking range was foul that would have been a dit. COVENTRY, EXETER and GLOUCESTER all did real shots the figures speak for themselves - hope the T45s are as good personally we should have gone for the ARLEIGH BURKE