Origin of "as useful as a chocolate teapot / fireguard"

Solution 1:

Eric Partridge and Paul Beale's Dictionary of Slang and Unconventional English (8th edition, 1984, s.v. much use as) gives an example of "chocolate teapot" from the Guardian, January 1979.

I haven't found any earlier examples, and don't know where it came about; though there are a few references to it on lists of Irish slang, I don't personally associate it with Irish English. The logic is presumably that if you used a chocolate teapot then it would melt, though research shows that this is not always true!

Solution 2:

The expression was used in The Guardian of 17th July 1978 in an article titled "Barnsley bashers face the chop", written by Michael Parkin:

Tourists that go to home games of Barnsley Town will hear some of the finest football wit and repartee in the land. Players are accused of being "as nimble as a stone trough" or "as much use as a chocolate teapot."

The phrase is repeated in The Guardian of 13th February 1980 in "Barnsley go down and the fans love it", again by Parkin:

What the visit will do for the public relations on the terraces at the Oakwell ground has yet to be seen. Barnsley's supporters are notoriously critical and much given to witty judgments.

A visit down the pit will not save a dawdling player form the kind of remark in which the Oakwell crowd specialises: "That's as much use as a chocolate teapot."

A 1981 Google Books snippet also points to the terraces as origin for this ironic simile. Desmond Morris's The Soccer Tribe (1981) describes 'The Jokers':

If the referee gives the opponents a penalty, he yells, 'When they circumcised you they threw away the wrong part.' If a player is not trying hard enough, he bellows, 'You are as much use as a chocolate teapot.'

Wikipedia confirms the date and says:

In 1978 Desmond was elected Vice-Chairman of the Oxford United Football Club. Interesting to note, later in 1981 Morris publishes 'The Soccer Tribe,' analysis regarding the world of professional football, or rather soccer, to Canadians and Americans.