Here is a summary of the arithmetic in the House of Commons (based on the assumptions that Anne McIntosh is returned as Conservative MP for Thirsk and Malton later in the month, and that when it comes to the appointment/election of deputy speakers, there will be one Conservative and two Labour MPs taking those posts).
The 641 MPs voting in divisions
Conservatives – 305 MPs
All others – 336 MPs
Labour – 256
Lib Dem – 57
DUP – 8
SNP – 6
Plaid Cymru – 3
SDLP – 3
Green – 1
Alliance – 1
Sylvia Hermon – 1
The 9 MPs not taking part in divisions
Speaker and three deputies – 4
Sinn Fein – 5 (will not take their seats)
So with 641 MPs taking part, 321 votes are required to attain a majority of one, meaning that 16 non-Conservatives are required to vote alongside Conservative MPs (assuming they all vote as one) for any Conservative proposal to be passed.
Jonathan Isaby