
Allegations—and, indeed, proof—of dirty tricks in the Lords are not unheard of. It turns out that the Habeas Corpus Act 1679 was passed thanks only to a particularly sly trick in the division lobbies when they voted:
Lord Grey and Lord Norris were named to be the tellers: Lord Norris, being a man subject to vapours, was not at all times attentive to what he was doing: so, a very fat lord coming in, Lord Grey counted him as ten, as a jest at first: but seeing Lord Norris had not observed it, he went on with this misreckoning of ten: so it was reported that they that were for the [Habeas Corpus] Bill were in the majority, though indeed it went for the other side: and by this means the Bill passed.
The clerk recorded in the minutes of the Lords that the "ayes" had fifty-seven and the "nays" had fifty-five, a total of 112, but the same minutes also state that only 107 Lords had attended that sitting. [Wikipedia]