Putting past commercial disasters behind him, Raymond Gubbay, the lord high impresario himself, is back in the West End with a five-week Gilbert and Sullivan season at the Gielgud Theatre, performed by the Carl Rosa Company and a line-up of celebrities to fill the comic roles.

The series launched with the most popular of the Savoyard operas: The Mikado, a light-hearted study of execution and torture oriental mode. At the start, a sly fragment of rehearsal dumb-show makes the link with Mike Leigh's brilliant film Topsy-Turvy, designs from which have been borrowed for Peter Mulloy's "authentic" Victorian production.

This device neatly diverted attention from a sketchy account of the overture and an initial uncertainty of style, not helped by a very Welsh Nanki-Poo (Andrew Rees) who took time to settle into the love interest role of wand'ring minstrel.

But the experienced Steven Page (Pish-Tush) and deft, lively conductor Martin Handley, guided the company back to Gilbertian crispness and Sullivanian classical pastiche. Chorus and Three Little Maids had charm, with Charlotte Page the simpering Yum-Yum and Sophie-Louise Dann an animated, no nonsense Pitti-Sing.

Complete sureness of touch is only really established by Eric Roberts as Ko-Ko, Lord High Executioner of Titipu, whose musical comedy experience brings genuine wit into play.

His little list has a cheerful array of irritating additions: mobiles, BlackBerries, reality TV, the Olympics and MPs' well-paid relations and undisclosed donations, all tossed off with clarity and panache (no need for surtitles here).

As the gruesome Katisha, Nichola McAuliffe came out in grand style as a creditable contralto and brought delicious neurosis to the part of the spinster "daughter-in-law elect".

This being G & S, the title role appears on stage well into Act II. Alistair McGowan, playing the benign Mikado as a cocktail of Fry, Paxman and Cleese, was worth the wait. His timing, inflection and comic expression, together with a well-trained light voice, showed how it should be done. If the performance is as yet a little stiff, by the end of the week I predict a riot.

Jo Brand, who plays the Sergeant of Police in the forthcoming Pirates of Penzance, was in the audience picking up tips. "I want to see someone else f*** up first," she noted as she took her seat. In the event, no one obliged.

• Until 9 February. Iolanthe, 11 Feb, and Pirates of Penzance, 18 Feb. Information: 0844 482 5130.