This explanation is odd because Jo Swinson, the Lib Dem MP, needs a pair because she has just had a baby and is on maternity leave. It is not as if she was planning to vote in some divisions, but not others. And Lewis did not not take part in most of the divisions on Tuesday night (honouring the pairing arrangement). But he did take part in the two closest ones (one of which the government won, and one of which it lost.)