The Mail on Sunday story describes how Mrs Quick runs a car hire business from their home.
The Quicks will, of course, have determined with their local planning authority whether this constitutes a material change of use in planning terms, and if so will no doubt have applied for planning consent for the appropriate use under the Use Classes Order.
If so, they will no doubt be paying business rates on the appropriate parts of the premises (garages, office) and these will comply with the requirements of health and safety and workplace legislation.
HMRC will also no doubt have carefully examined Mrs Quick's tax returns to ensure she is not overclaiming on domestic expenses for the business.
And no doubt those 'ex police drivers' will not have been paid cash-in-hand but will have either produced the appropriate self-employment documents or will have been properly employed by Mrs Quick.
I can't believe an officer as senior as Bob Quick could condone any breach of the law by his own wife. That would be corrupt, wouldn't it?