What’s the secret of perennial freshness? No, I’m not asking the question beloved of toothpaste adverts. I’m talking about singers and actors who’ve played the same part countless times, yet each new performance seems freshly minted. Paul Nicholas has long since discovered that secret, having starred as the Pirate King in Gilbert and Sullivan’s Pirates of Penzance on and off for many moons.

Originally associated with Joseph Papp’s hotted-up version of Pirates, Nicholas is currently starring in Carl Rosa Opera’s more traditional production. Now sounding a touch huskily sexy (to judge by the wholehearted enthusiasm of the ladies around me in the Milton Keynes audience), he still seems as fresh as a daisy as he explains the difference between “orphan” (as in without parents) and “orr-fan” (as in frequently, when spoken in a posh accent). For this Pirate King and his cutlass-brandishing crew are really noblemen “gorn wrong”.

Directed with an affectionate and humorous touch by Peter Mulloy, the fun begins during the overture, when Major General Stanley (Barry Clark, splendidly self important, and expert at rolling his vowels) is seen out for his morning swim. Such is the effort involved, he quite fails to notice the approach of the pirate ship. Director Mulloy (also responsible for the colourful set and costume designs) provides several other choice comic scenes: the consternation as the pirates discover a bevy of beautiful maidens about to risk taking off their stockings and going for a paddle is hilariously handled. Also memorable are the routines involving the Sergeant (Bruce Graham, pompous and luxuriantly mustachioed) and the chorus of policemen — the fight with the pirates, involving clashing cutlasses and truncheons, is a classic piece of comic timing.

At the heart of the storyline is Frederic, the apprentice pirate who has served his indentures and is about to become a free man. But he was born in a leap year, so technically has only served for five of his 21 years. Kevin Kyle sings the role with great feeling — his duet with the Major General’s daughter Mabel (Rebecca Knight) is one of the high spots of the evening. Meanwhile, Rosemary Ashe vividly portrays Frederic’s nursemaid Ruth as a robust lady who has been round the block many times.

In the pit, Oxford-born conductor and Radio 3 presenter Martin Handley directs exemplary accompaniment — plenty of sparkle, but the singers are never upstaged. Carl Rosa’s Pirates may lack the ultimate in oomph, but it’s a very musical and highly entertaining production.

The Pirates of Penzance continues at Milton Keynes Theatre until Saturday. Tickets 0844 871 7652 or online at ambassadortickets.com/miltonkeynes