The part of the play which I believe you're referring to can be read here, and refers to the actions of Walter Harrison, then a government whip in a committee stage vote, not a vote in the main Commons chamber.
Please. Mr Speaker, there's been a difference of opinion regarding the
votes on two bills at committee stage. Amendments to the Education
Bill were being voted on in Committee Room 10, while amendments to the
Finance Bill were being voted on in Committee Room 14. Mr Harrison
here had been the pre-selected Whip present at both committees -
Yes, right, I voted in 14 and then I ran down the corridor to 10 to
vote there and -
Just as I was closing the door.
Just as the doors were being closed, and locked, as is the custom -
As is the law. Committee room doors must be closed and locked during
a vote and -
And he didn't make it -
And I did bloody make it!
A sizeable chunk of Mr Harrison did make it, Mr Speaker.
Cocks / Harrison
Si - a 'sizeable' chunk, you say? Which chunk?
My whole body, both arms, and my left leg, but my right leg got caught
in the door as he was closing it. Look, I've got a bruise and
And then he wouldn't leave so that the doors could be closed -
Because I'd made it into the room. Look at that, see, purple, like a
What was the vote without Mr Harrison?
Cocks / Serjeant
22 to 22.
Serjeant, would you say that the overwhelming majority of Mr Harrison
was inside the committee room?
Well. Uh, yes, I suppose I would, Mr Speaker.
Very well, I declare the vote for the government, 22 to 22 and three
The committee stage is where changes to the text of a bill are made, and happens between the second and third readings of the bill being voted on in the main Chamber. This specific instance is described further in the obituary of Walter Harrison in the Telegraph:
One day in May 1968 he was whipping on two Committees at once when a
vote was called on the Finance Bill. He arrived just as the door was
closing, forced his way through and voted. When the Shadow Chancellor
Iain Macleod challenged his vote, Harrison said he had been
three-quarters in and had pulled his leg in after him. The chairman
declared the vote carried by 22¾ to 22.
So this is a fairly accurate historical account. However, in reality, the Speaker was not involved, the person who made the decision was the chairman of the bill committee, and he did so not because he thought the government's political case was strongest, but because he thought that Harrison got the majority of his body through the door before it was locked.