Today in the UK House of Commons, Conservative MP and PM candidate Jeremy Hunt failed to take part in an important vote. He said:
I missed votes today because I thought I was slipped and it turns out I was not.Apologies to my colleagues & Whips Office.
What does "slipped" mean in this context? It seems to be an unusual and possibly specialist meaning - I can't find any meaning in the usual dictionary sources which covers this. It might be a term from UK parliamentary jargon, or as one person on Twitter claims from UK private school slang.