In our slowly developing tour of ill-advised sequels, it is time to examine Guy Hamilton’s 1978 effort Force 10 from Navarone. A long-delayed follow-up to the popular hit The Guns of Navarone, it took so long to head into production – 17 years – that the entire leading cast was too old to reprise their roles and had to be replaced.

Following the success of their Navarone mission, Major Keith Mallory (Robert Shaw) and Sergeant John Miller (Edward Fox) are sent back out into the field: this time to track down and kill the German spy Nicolai (Franco Nero), who informed on their original mission to the Nazis and who has infiltrated the Yugoslavian resistance. To get into the field, they hitch a ride with an American mission commanded by Lt Colonel Mike Barnsby (Harrison Ford).

As with Grease 2 and Blues Brothers 2000, which I reviewed recently, Force 10 from Navarone was a commercial and critical failure upon its 1978 release. That failure is hardly a surprise. Not only was Force 10 made more than a decade-and-a-half late, it genuinely feels like it as well. Hamilton, best known for his successful James Bond films Goldfinger, Diamonds are Forever, and Live and Let Die – not to mention his 1969 war epic Battle of Britain, directs a picture sorely at odds with its post-Star Wars release. Popular cinema changed radically during the 1970s, and for all his artistic strengths Hamilton simply cannot keep up to date. His largely British cast perform their roles in the classical British style typified by Hammer Studios and the BBC – it is an actor-spotting marvel for fans of Doctor Who – and then chafes palpably with American imports Harrison Ford and Carl Weathers. The first act is dreadfully mannered and awkward. Ford in particular looks one step away from calling his agent, so out of synch is he with the rest of the proceedings. Matters are not helped by Ron Goodwin’s handsome yet entirely outdated orchestral score. Take Ford out of the equation and there is nothing to indicate Force 10 was made after 1965.

Thankfully after a gruelling opening, the film manages to get Ford and Shaw’s characters away from their squad and both the energy and entertainment value shoots through the roof. With sterling and charismatic supporting work from Weathers and Fox, Force 10 becomes a genuinely entertaining war adventure. It is the kind of film where old-fashioned words like “rollicking” best apply, and the interplay between characters improves as it goes. It was a terrible film for its time, but a delightful diversion for lazy Sunday afternoons. Its charm is, in the end, immense.

It is a modest confection for James Bond enthusiasts as well, since Guy Hamilton casts both Barbara Bach (The Spy Who Loved Me) and Richard Kiel (also Moonraker) among the enemies. Bach stands out of the film like a sore thumb – it’s not her looks, it’s the make-up and perfect hair in a war zone – while Kiel proves once again to be excellent henchman material.

Force 10 requires audiences to get over a hill of mediocrity in its opening half-hour, but for those who persevere there is a pleasing if old-fashioned entertainment to be found. For those who have outwatched other, much better, war movies like The Dirty Dozen, Where Eagles Dare, and indeed the original Navarone, it serves as a broadly satisfying alternate.