Exhaust smell in cabin

[SLonsdale]

Over the last few days I have noticed an exhaust smell in the cabin. It is really noticeable on cold startup. Hardly noticeable when moving and a little whiffy when idling. The car is not down on power and not making any unusual exhaust noises.

I obviously know there is an exhaust leak but I can't find it. As I am caravanning in the peaks at the moment a major repair is not feasible.

Does anyone know the most likely place for a leak? The car is totally standard