Most London homes heat with gas boilers, and in flats and conversions that usually means a combi in a kitchen cupboard. Breakdowns cluster in the first cold spell each autumn and again in deep winter, when every heating firm is busy at once.
Access and parking make London jobs slower than in other cities: controlled parking zones, the Congestion Charge in the centre and the London-wide ULEZ all shape which boroughs a van can cover in a day.
Newer blocks often run on communal or district heating, which is a different job. Heat pumps are growing in outer boroughs with houses and gardens, and the Boiler Upgrade Scheme (a government grant) requires an MCS-certified installer.
Gas work must be done by a Gas Safe registered engineer, and customers do check.