Why can’t some parliamentary select committees get female witnesses?

In their nearly eponymous 1995 hit, Reverend Black Grape, I’m a Celebrity runners-up and Bargain Hunt cheats, Black Grape, asked ‘Can I get a witness?’ In 2019, why is it that some select committees seemingly find it difficult to get female witnesses to give evidence at their sessions? Marc Geddes, Mark Goodwin, Stephen Holden Bates and Steve McKay find that some of the answer may well be found in the gendered make-up of the committees themselves.