Edward John Dent, engraving by Charles Baugniet, 1853.
The Westminster Clock was built and designed by Edward John Dent, who made many of the clocks used by the ROG and now in the NMM collections. His recommendation as maker, and much of the design was, however, suggested by George Biddell Airy, the 7th Astronomer Royal.
George Biddell Airy, engraving by Thomas Herbert Maguire, 1852
Airy had frequently collaborated with Dent on Observatory equipment and to try out his own ideas in clock-making theory. Not least, they had already collaborated on another important turret clock, which was made for the Royal Exchange. This was so successful that Dent remarked, "The mechanical world in my opinion lost its greatest genius when Mr. Airy became an Astronomer....".
Perhaps most importantly, from the ROG perspective, it was Airy who drew up the specification to which both the Royal Exchange clock and the Westminster clock should conform. They were to be far more accurate than previous public clocks of this type, for Airy specified that the first stroke of each hour should be accurate to a second. This was to be regulated to Greenwich Time, by being checked twice a day at the ROG via telegraph. As historian of science Jim Bennett explains, Airy not only devoted a lot of time to these clocks, but "it is clear that his general intention was not simply that another clock should be built, but to effect a change of attitude to public timekeeping".
Westminster Clock Tower, watercolour by William Lionel Wyllie (late 19th/early 20th century)
Things did not proceed quite as easily as they had with the Royal Exchange clock and, perhaps because of lack of time, Airy asked the MP and amateur clock-maker Edmund Beckett Denison to assist in overseeing the project. Differences between the two led to Airy resigning in 1853 - but his demand for accuracy and the link to GMT remained.
See the UK Parliament website for an account of the various other delays that hit the building of the clock, the tower and the bell - and you can see some fantastic images of the Clock Tower and the workings of the clock on the BBC website.