I keep hearing it but I can't see any evidence.
Earlier this week I travelled almost the whole length of the District Line, from East London, through the City and West End out to Wimbledon and back, over the course of about 10 hours.
I'd say at least 97% of women, of all ages, from very young to not so young at all, were wearing either skinny jeans or very slim leg trousers. I saw one group of young women all wearing wide leg, ripped jeans and a few wearing joggers. That it. This would be a mixture of tourists, Londoners going about their business, working people and people out for the evening.
I had coffee in the City, lunch in a West End restaurant, drank in a swanky West London pub, attended a sporting event. Honestly skinnies everywhere.
I looked because I'd worn a skirt rather than skinny jeans and it was raining, so wide leg ones are horrible. Didn't see many skirts either
Certainly very little evidence that no one's wearing skinnies any more.