Alsacienne I have worked for 4 UK airlines over the years. All of them called for the removal of high heeled shoes only. The rationale being that these have the potential to damage and potentially deflate the slide on descent making it unusable for anyone else.
I have never heard of any UK airline asking pax to remove all their footwear in an evacuation. Legging it out of a downed aircraft when there would be all sorts of debris on the landing site would not be easy in barefeet and would slow the flow of evacuating pax on the ground.
Hope that helps
