Found something.
Soft tenancy agreements in houses of multiple occupation where the all-in value of board, lodging, and services including use of common rooms exceeds 354 pounds a month must be declared to HMRC. It's likely the influx of immigrants who are accommodated in houses of multiple occupancy have caused HMRC to miss out on taxes.
This *might* be what the review has in mind. Nothing definite, still researching at this point...
