Some of the fragments are over 350 years old...

According to The Museum of London, the earliest account of a pipe being used to smoke dried tobacco in England dates back to the 1570s.

Disposable pipes were hand-made until a way of implementing moulds was introduced to speed up production. By the end of the 16th century tobacco smoking had become so popular that pipe-making factories were popping up everywhere – in 1619 there were over 100 clay pipe manufacturing companies in London alone.

Each pipemaking company had its own mark or personal initials and these were sometimes imprinted onto the pipes on the stem or bowl, but more often on the base or the heel.

These cheap pipes clogged up after only a few uses and so smokers just tossed them away and started a new one.

More info about clay pipe in general available from The Society of Clay Pipe Research.

Due to their fragility it is rare to find a discarded pipe in its complete state these days, however, at Keen's Steakhouse in New York the ceiling of the Lillie Langtry Room is covered in old Dutch churchwarden pipes. Thanks to Vidiot for these images. I particularly like this shot. According to Keen's website, they have the largest collection in the world.

A lovely coincidence... a C19 pipe-maker called Jane living in Parker Street. Also from Essex and moved to North London!

Did you know that clay pipes were not just used for smoking? See this link.

Great footage here from a BBC antiques programme featuring an item about the Broseley Pipeworks showing how clay pipes were made at the Broseley Pipeworks... NB start viewing about 10 minutes in.

Clay pipe art – hanging on the wall of the cafe within the Isles of Scilly airport there is an artwork created from thousands of clay pipe fragments found on the beach see page 16 in here

Shown below is a collection of images showing some of the more interesting bowl and stem fragments I have found along the Thames. See them also here with more links and info.