Megan Mullally will forever be known as Karen Walker from Will & Grace. So branching out, particularly with a UK audience – most of whom won’t know that she has a separate recording strand to her career, let alone have heard of the band she performs with, Supreme Music Program – was always going to be a tricky endeavour.

Many fans, myself included, will have turned up to the Vaudeville Theatre expecting at least a pinch of Karen and a dash of Walkeresque comedy, an expectation reinforced by fliers for the show adorned with quotes from Will & Grace and posters announcing the awards Mullally received for her performance in the series. Would she be anything like Karen in real life?

The answer is a very definite no, and any other questions about Karen’s influence on proceedings are quickly answered when Mullally herself confirms that “Karen is not coming” tonight, news that was greeted with an initial burst of applause and polite laughter, followed by a fairly palpable air of disappointment as it settled in that she wasn’t kidding.

Aside from the occasional wry aside, Mullally doesn’t kid much. Unlike Karen, she’s quite serious and reserved. There isn’t much chatter at all between her songs, and certainly not much about the songs themselves (she freely admits her own research deficiencies). The evening’s main moments of levity are provided by the occasional cat-calls from over-amorous fans, which illicit naturally witty and sharp comebacks from Mullally and help to relax proceedings.

All that said, if you can put aside your expectations from sitcom-land or other semi-confessional cabarets and approach this evening for what it is – almost an informal jam session with a soulfully versatile singer and her six talented backing musicians – you’ll find much to enjoy.

Mullally’s “march of death” set of songs, though pretty thematically downbeat throughout, does contain a nice variety of styles, including blues, country and western and pop with a couple of rock numbers thrown in for good measure. “Wind and Rain”, a deconstructed “Ave Maria” and “I Belong on the Stage” are stand-outs vocally and atmospherically.

It’s a shame that, given her impressive Broadway credits including How to Succeed in Business Without Really Trying and Young Frankenstein, and her natural character-acting ability, Mullally whole-heartedly “eschews musical theatre” in her selections: Sondheim gets a look-in but only with a little-known song called “I Remember” that he penned for a short-lived TV programme.

The Vaudeville is a fairly large theatre – and, given Mullally’s Will & Grace popularity, there should be no problem filling it for such a limited run – but, for what she’s doing here, a more intimate environment would have been more conducive. And maybe just a few Karen jokes to pep things up?