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Cardiff Pierhead Clock

After a long and complicated series of negotiations (and a large piece of luck) by a small and dedicated group, the turret clock movement built in 1897 by William Potts and Sons of Leeds finally returned home to Cardiff on 27th July, 2005. The movement used to be in the tower of the Pierhead building (see right), which was built for the Marquess of Bute as his Docks Office. The building and the clock dials were designed by William Frame, an assistant to the architect William Burges who was responsible for the design of Cardiff Castle and Castell Coch, for the Marquess. The Pierhead clock is something of an icon in Welsh society, as the 6ft 6in dials are seen by the people of Wales every time they tune into the Welsh TV news.


The clock mechanism (seen below) is probably the last one to be made by Potts, with an escapement similar to the one designed by Edmund Beckett Denison (Lord Grimthorpe) the designer of the world famous Palace of Westminster clock in London, known commonly as Big Ben. The total weight of the clock is about 1000lbs, the flat bed frame being 52" wide by 24" deep with a 72" pendulum. As in the Westminster clock, this clock has used a double three-legged gravity escapement and a temperature compensated zinc/iron pendulum.

The escapement is of ingenious design in that the impulse given to the pendulum is due to gravitational forces induced by the two 'arms' that can be seen expanding and contracting as the clock 'ticks'. These 'arms' also lock the train on each beat, preventing the movement from running down in an uncontrolled fashion. The reason Grimthorpe used this design was because in large clocks, any unusual forces acting on the hands, such as wind or snow for example, could dramatically affect the accuracy of the time-keeping. This is not good on a public clock. To increase the accuracy of the clock further, the zinc/iron pendulum compensated for changes in temperature from summer to winter. You will still see a small 'tray' on many pendulum rods on these large clocks on which the clock winder will place coins or nuts to fractionally alter the rate at which the clock beats to correct any minor errors in timekeeping. These clocks also require very heavy weights to give a full week's duration. Many have now been converted to automatic winding, using electric motors. These wind much lighter weights which operate wheels further down the train, but have to be wound more frequently, perhaps hourly or more.


The original bell, with its Welsh inscription Gwell angau na chywilydd [Death before dishonour], can still be seen at ground level in the Pierhead building. The name W. Potts and Sons is clearly cast on the outside.


The story of the clock's retrieval is fascinating. Bill Linnard, author of several books on Welsh clocks (see Research page of this website), wrote an article in Horological Journal ('Old Dials Evoke Memories of Tiger Bay' - April 2004). In the Journal was a mention of the Pierhead clock. BHI member Alan Heldman in the United States, saw the article and met the HJ editor, Tim Treffry at an NAWCC meeting in Portland, Oregon. Alan told Tim that he had purchased the clock some 30 years ago with the intention of restoring it but had never found the time or enough room to operate the movement. After some thought, he generously offered to sell the clock back to Cardiff subject to it being restored and put on display for the people of Cardiff and Wales. He and Bill Linnard exchanged many emails until a satisfactory repatriation programme was reached. Bill then had to find someone interested enough to take on the task of buying the clock and getting it back to Wales. He eventually found Cardiff City Council's Special Projects Department, headed by Pat Thompson. Pat and his team then had the challenging job of finding funding to pay for the clock and seeking sponsorship to have the 1000lb mechanism shipped over to the UK. Many sponsors were involved, but to mention three - Cardiff's connection with the Norwegian Church led to the clock being shipped across the Atlantic for free by the Norwegian shipping company, Star Shipping. Cardiff Stevedoring arranged to receive the clock into Cardiff Docks and its final overland transport to the Old Library was courtesy of Brains Brewery on a vintage brewer's dray.

Summer Smoking Room, Cardiff Castle

Summer Smoking Room, Cardiff Castle

On Friday 23rd September a special event was organised by Cardiff City Council in the Old Library to celebrate the return of this important clock. The day began at 2 p.m. with a tour over the clock tower of Cardiff Castle, visiting firstly the Winter Smoking Room, the Bachelor bedroom, and above this, the Summer Smoking Room. The clock mechanism is located on a floor between the last two. The turret movement (seen below), which drives four dials, was made by Dent & Co of London, who also made the Palace of Westminster clock.  It strikes the hour on a bell which is mounted in the same room, in front of the movement. The escapement is the same as the Pierhead clock and the chains which you can see going up to the right-hand corner of the image are part of the automatic winding mechanism.

The next visit was to Cardiff City Hall with its beautiful marble hall (seen below). There is a fine wall clock by Gillet & Johnston of Croydon in the Council Chamber. The same manufacturers made the turret clock which is mounted high in the tower. Several beautifully made cast-iron spiral staircases have to be negotiated to reach these dizzy heights. When one finally reaches the clock room one is confronted with the most wonderful mechanism, both impressive in size and appearance. Most of it is made from the finest brass (or gunmetal) and it shows. Again the double three-legged gravity escapement is used and in this case the pendulum is enclosed in a wooden box.

Unlike the other clocks, this has three trains, the extra train driving a quarter-striking mechanism producing a Westminster Chime. The plate controlling the chimes can be seen in the right foreground, with the hour striking plate on the far left. The long tube running along the base of the image is a tubular oil heater, which provides just enough heat to keep condensation off the movement and prevent rusting of the iron parts. Again you can see 'bicycle' chains running up from the movement, which automatically wind the clock. The sheets on the wall on the left hand side are maintenance records left by Smiths of Derby who service the clock. Peter Sully, Managing Director of Smiths of Derby, explained the clock mechanisms to us, and City Council staff gave us a guided tour of the buildings.

The fine turret clock movement by Gillett and Johnston in the clock tower of City Hall

At about 5.30 p.m. we were treated to a tea in the Old Library followed by two excellent lectures and a good chance to inspect the repatriated movement. The first speaker, Michael Potts became totally absorbed in his family history which traced the family business from its establishment by William Potts (his great-great grandfather) in 1833. William met Lord Grimthorpe (a QC and talented amateur horologist) in the 1840's. Following the design of the gravity escapement the Potts turret clock business expanded and they moved to larger premises in Leeds. With the expansion of the railways and the introduction of standard time there was a demand both for large public clocks as well as clocks for the railways, schools, hospitals, libraries and other public buildings. The decline started with the First World War with the introduction of electric clocks and cheap imports. The business was finally sold in the 1950's to Smith of Derby who also bought out Joyce of Whitchurch.


Peter Sully, Managing Director of Smith of Derby, gave us a brief account of the Company's history and showed us how the clock industry has evolved with the introduction of electricity and modern digital electronics. The company makes and repairs all types of clocks, but Peter concentrated on the heavy turret clock side of the industry. He showed us a modern electric turret clock movement which would carry out all the functions of the Pierhead clock, yet he could hold it easily in one hand! He stressed the modern trend of converting these valuable ancient movements to automatic control without imparting any non-reversible structural changes to the original. He showed us some ingenious winding mechanisms, but the most amazing piece of equipment was one that was fixed to the pendulum bob and was controlled by an adjacent stationary master clock, which imparted a regular signal to the bob mechanism, raising or lowering a small weight enough to make minute changes to the rate of the clock so that it remained perfectly in time. A further development was a pendulum stop which holds the pendulum for an hour when the clocks go back in the autumn. He did not, however, tell us how they automatically go forward again in the spring!


After the close of the exhibition, the clock movement will be professionally restored to full working order by Smith of Derby. It will then be returned to Cardiff and become part of a major public work of art designed by an international artist in conjunction with Cardiff Council, and displayed at the Millennium Plaza in Cardiff Bay.

Michael Potts

Peter Sully

The group most involved in getting the Pierhead clock to Cardiff - left to right Timothy Treffry (editor of Horological Journal), Cllr. Nigel Howells (Cardiff City Councillor for Sport, Leisure and Culture), Bill Linnard (Chairman of the Wales and Marches Horological Society) and Pat Thompson ( Cardiff City Council Special Projects Department).

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