"That's not Surrey" I said as we watched our tortured antihero climb a hilly street lined with cottages in buttery Cotswold stone- and "That's not Surrey" I said again as his car drove through a rolling landscape of multicoloured fields and ample prospects. I was right. The programme had been filmed out west, with Bristol pretending to be London and Gloucestershire pretending to be Surrey. Bristol just about pulled it off- because one big city is very like another- but Gloucestershire villages and landscapes are nothing like their Surrey counterparts.
Knowing the difference between Gloucestershire and Surrey is a gratifying side effect of extensive church-crawling.