I don't know the U.K. at this level of detail but didn't you go "all in" on socialism after WII? As far as the government set minimum wages, aren't you already talking about something other than a free market?

Anyway, if the minimum wage is set by the government at a level above the value of someone's labor, you (the company) are going to:

Do without (movie ushers in the US).

Automate.

Move the work offshore.

Hire as few as you can for as little as you can when you can't do without, which these retail jobs might be an example of.

I'm not at the moment discussing the merits of a minimum wage, just pointing out that is has well established consequences.