From journalist Nicholas Watt on Twitter:
With two Tory MPs supporting Theresa May’s deal she has one breakthrough: enough tellers for her #Brexit vote
I believe this is a reference to some system in use in the House of Commons. What is Mr. Watt referring to here? That two MPs need to be in favour to have a vote at all? Two MPs to count the votes?
(I'm aware that the tweet is humorous — but I don't understand the joke)