Retailers have warned that the cornerstone of British social manners, the teapot, is dying out.

Sales have plummeted as people opt to make tea in their mugs – to the horror of polite society.

Debenhams, which is launching a campaign for "civilised" tea-drinking, said teapot sales had halved in the past five years, while demand for mugs had trebled. Tea served in a teapot and poured into China cups is the traditionally British way, but modern drinkers prefer what the retailer called a "lazier method".