More than 25 years ago, my local branch of the Ramblers insisted that a mat for sitting on was compulsory kit. Sadly, I'm not longer a member. And I have long since stopped using a mat. I was probably one of the youngest members (mid-twenties) back then, so just did as I was told. I was gifted a blue mat on permanent loan from an unnamed walk leader. Other rules; don't wear your boots on the coach, and don't wear your coat on the coach or you won't feel the benefit when getting off.