I doubt they are mining bitcoin, probably the police just making assumptions at this point. Also there is no way that this setup's electricity would cost that

I doubt they are mining bitcoin, probably the police just making assumptions at this point. Also there is no way that this setup's electricity would cost that little in UK. The average cost of electricity bill for an average household is around £700 a year. If they paid, this would literally be thousands if not 10k+ a year in electricity bills.