Pimlico Plumbers had a record three months leading up to Christmas with sales of £5m, up 12% on the previous year.
The figures put the plumbing firm on course for record sales of more than £18m for the year ending in May, £1m up on a year before.
Charlie Mullins, who founded the firm in 1979, said the growth was due to a rise in consumer confidence rather than weather-related callouts.
