A quintessentially British item accidentally invented by New York merchant Thomas Sullivan celebrates its centenary this month.

In June 1908, tea dealer Mr Sullivan was sending samples to potential customers when, to cut costs, he put a few pinches of loose leaves in several small silk pouches.

The confused clients received the samples and, unsure of the instructions, reputedly dunked them into hot water, and the tea bag was born.

Previously, all tea had to be painstakingly strained before it could comfortably be drunk.