IT was the gig of a lifetime. My big shot at stardom. No longer would I just be Kevin Foster, Parliamentary Under-Secretary of State for Wales. I would be proud defender of the Prime Minister, his best supporting actor at a time of national crisis. I would be in the papers, on the telly, trending on Twitter, he said. “You’ve got a bright future ahead of you,” he said. Just stick to the script.

It wasn’t going to be easy. Some might even say I was tasked with defending the indefensible. Why wasn’t Boris Johnson in the Commons himself, they asked, to respond to their urgent questions about his use of language in parliament on Wednesday night, and his utterly crass remarks about murdered MP Jo Cox?

I’ll tell you why – because a little-known MP with a big dream was ready to step into the limelight. To go from understudy to matinee idol overnight.

Silence fell as I began my first solo number, setting out the Government’s position that threats and abuse are bad. The audience were stunned by both my vocal talents and my ability to completely ignore the question I had been asked. I’m sure I heard one cheer of “BRAVO!” – but that MP clearly needs to brush up on his French because it sounded more like “DARVO!” (This sort of thing shows why our Government is right to be investing in education).

I kept them captivated with a verse about the creation of a brand new offence, which means that when people do things like use the exact words spoken by the Prime Minister when detailing plans to kill candidates in the run-up to an election, they will be in even more serious trouble. By the time I reached the second chorus of “Threats are bad/ abuse is bad/shouts of ‘Tory scumbag’ make me sad”, toes were tapping and shoulders were bobbing.

Of course, Labour MP Jess Phillips had to spoil the moment by butting in with some tone-deaf warbling about a top-level strategy to divide the nation using carefully chosen language like “surrender”, “treachery” and “betrayal”. What would I know about such things? I’m just a humble MP with charisma, stage presence and exceptional diction – I’m not invited to the strategy meetings. I don’t know about any plan to pit the people vs Parliament in order to force through a No-Deal Brexit. This was the first I’d heard of any such thing.

She claimed that the bravest, strongest thing for Boris Johnson to say was sorry, but that word was definitely not in the script he’d given me. Neither was the phrase “calm and dignity”, but here I put my considerable improvisation skills into practice. Yes, it might have sounded like those words literally caught in my throat as I uttered them, but I can assure you this was merely acid reflux from the three cans of Red Bull I had downed an hour earlier.

The challenges continued. Do not underestimate the demands of being what we in the trade call a “triple threat” – ie, someone with the ability to be simultaneously standing up, talking, and deflecting difficult questions. These were coming thick and fast. Surely, they said, it was wrong for the Prime Minister to dismiss as “humbug” the fears of MPs who were receiving death threats quoting his own inflammatory language? And wasn’t it a grotesque mis-step to suggest that delivering Brexit was the best way to honour the memory of Jo Cox, who was murdered while campaigning for Remain?

The strategy I devised here was to simply elongate the opening words of each of my responses. “Thank youuuu … Misterrrr … Speakerrrrrr” I droned, buying myself precious seconds to think how I could steer my way back to the chorus without missing another beat. Doubtless this method will one day be taught in conservatoires around the word, and the Foster name will be up there with Stanislavski, Brecht and Artaud.

I had some creative suggestions for the next part of my speech, but there must have been a problem with the Prime Minister’s email on Thursday morning because he didn’t get back to me in time to approve my amendments. I felt that the best way to reiterate what we wanted to communicate would have been through the medium of rap, which everyone knows is the best way to make white politicians seem cool and progressive.

I’m sure the future librettist of Brexit – The British Musical would have appreciated being given a head start. Presumably Idris Elba will play me in the West End premiere, so I took the liberty of sending him some rhymes to start rehearsing: “We are planning to legislate/around efforts to intimidate/around about election time/it’s gonna be a major crime/to say I want to injure you/ for expressing a political view.” Wicked, innit?

I concede my time might have been better spent rehearsing the approved version of the speech. Robert Buckland, the very much alive Lord Chancellor and Justice Secretary, was not particularly pleased with my accidental reference to his assassination. Of course I meant Robert Bradford, the Ulster Unionist politician who was shot dead in 1981. Some might say it was appropriate that I managed to disrespect the memory of a murdered politician while standing in for a Prime Minister who had done the very same thing just hours earlier, but clearly this was different as I did it by accident whereas he did it on purpose.

So is his use of inflammatory language deliberate too? “Stick to the script,” he told me. “You can be the good cop.” “Thanks boss,” I replied. “But wait – what does that make you?” There was no reply. He was already gone.