This certainly happened in Leicester to a degree - in Vincent Hokyoak's book "But For These Things" he describes the culture clash in detail including a violent incident in The Three Cranes pub.

It didn't help the fact that the American GI private was paid three times the rate of a British private.

Many of the personnel in Leicester were airforce which meant a high probability of being killed which may partially account for the loose sexual behaviour ( like British soldiers in France in WW1) - prostitutes would come up from London by train and congregate around the Clock Tower.

It would seem that the black troops were not combat troops but acted in a support role.

Leicester had often been at the forefront of equal rights issues including local campaigns against slavery and, in general, the public resented US imposition of its practices on British soil.