Going to London on Saturday and have tickets for the musical Chicago on Monday night and Les Mis on Thursday matinee. What is the attire for the evening shows? Suit and tie? I was thinking of wearing some type of Dockers with a nice shirt and maybe a tie. Is that too casual? Maybe a sweater (I hate them and only own one) ?

I would rather not pack a suit to wear only once. I assume the matinee attire would be similar/less than evening.

Thanks!