Two years without the engine ever stretching its legs
A car kept around Streatham Vale or the high road near the ice centre and the old Streatham Hill Theatre spends its life at 20mph on a red route, pulling away from one crossing to stop at the next. Mitcham Lane is steadier but hardly open road. The engine makes a small fraction of its power almost all the time, and combustion temperatures stay too low to keep the plugs and the inlet tract burning clean.
Two years of that leaves deposits on the plug insulator and a worn, widened electrode gap, which the ignition coil covers up by working harder until it stops being able to. Direct-injection petrol engines fare worst, because they also accumulate carbon on the inlet valves in this kind of use. The first signs are undramatic, a longer crank or a hesitation pulling out onto the high road, and the last one is a misfire that destroys a catalytic converter.
At the major service we fit plugs to the exact type, heat range and gap specified for your engine, from NGK, Denso or Bosch, torqued to figure and with the coil boots checked. Diesels get the fuel filter instead where there is a serviceable one. The brake fluid is changed completely from a sealed container, with moisture tested before and after, which matters on a car whose brakes work constantly and never cool to ambient.
The full service is included: oil, oil filter, air filter, cabin filter, wheels off with brake measurements recorded, coolant and battery tests, a fault code scan and a road test. Allow most of the day. Given the trip is about twenty minutes each way out through Mitcham, collection and delivery from Streatham can be arranged, and you get a written quote before anything beyond the service begins. Repairs carry our 3-month workmanship guarantee as usual.

