When John Marquez. Replaced Steven Wright as the town's vapid, clumsy, bumbling PC (British term for Police Constable) on DOC MARTIN, it was obviously intended that the physical comedy be heightened on the series since Wright's PC Mylow was equally brooding as he was silly while Marquez's PC Penhale makes Inspector Clouseau seem like Dirty Harry...
Neither were perfect characters... Mylow's sexual problems were just odd while Penhale more or less goes from a goofy to completely unrealistic character...
But now they're together, and somehow Penhale manages to be the smarter one, investigating a stolen tractor, which is actually the b-story to Doc having to once again go through the steps of proving he can be a legit doctor by reluctantly cowtowing to those beneath him...
So this episode is as if Three's Company had Don Knotts and The Ropers together, which... well... wouldn't really be necessary, nor was Mylow's return but, it's nice to see him again since those first four seasons... known as the Aunt Joan years... in which he was half of, are the best of the series.