I glanced across the stage at Mark Fowler from EastEnders vigorously stretching his glutes in a pair of scruffy Lonsdale tracksuit bottoms, looked down at my own medieval tights and bloomers, and wondered what on earth I had signed myself up for.

Richmond and Twickenham Times:

Spamalot, the musical based on Monty Python and the Holy Grail, has a character named Sir Not Appearing, who briefly joins the Knights of the Round Table onstage, apologises then leaves. And, Not Appearing for the first time at Tuesday night’s performance at the Richmond Theatre, was me.

Once wardrobe manager Euan had helped me pop on my costume and told me a few tales from his 34 years working behind the scenes in musical theatre - apparently the Wizard of Oz production team would forever be opening cupboards to find highly-sexed dwarves having fun inside - I joined the rest of the cast onstage to practise my entrance.

I had interviewed Joe Pasquale, who plays King Arthur, by phone a few weeks earlier for the show’s preview, but did not for a moment expect him to know who I was, so was pleasantly surprised when he bounded across the stage to shake my hand and squeaked: "Hello Georgey!"

Everyone told me my part would be a piece of cake - I had to walk on, put my hand on one of the knights’ shoulders then shout "sorry!" and walk off - but when it came to my cue I was absolutely terrified. Richard Meek, who plays Sir Galahad, gave me a few words of encouragement as he adjusted his wig, and I was pushed out on to the stage. "Sorry!"

Massively relieved that my pivotal scene was over and the pressure was off, I clambered out of the armour and went to join my friends in the audience to enjoy the rest of the show, which was hilarious.

Pasquale told me in our interview that he loved every minute of being part of the production, and it was clear he and the rest of the cast were having a great time on stage, often almost visibly vibrating with the effort to keep from laughing.

Euan told me beforehand that Pasquale was notorious for "corpsing", trying to make the others laugh onstage mid-performance, and it certainly seemed the performers were having as much fun as the audience.

Classic Monty Python lines were delivered with perfect comic timing by the talented cast, who delivered an enormously enjoyable evening and gave me a renewed respect for the stage performers.

Spamalot; Richmond Theatre, Little Green, Richmond; until January 31; evening shows 7.30pm Friday and Saturday, matinee show 2.30pm Saturday; £13.40 to £48.90; visit atgtickets.com/venues/richmond-theatre.