By the time that the firm of Muzio Clementi & Co was emerging from the ashes of the bankrupt Longman & Broderip, most of the output was of 5½-octave pianos. These exploited the patents of John Geib for the escapement action (1786) and William Southwell for the 'additional keys (1794) - both of which were exclusively licensed to L&B. However, production of simpler five-octave instruments continued, although probably not at the main Tottenham Court Road factory. It is likely that they were sub-contracted to one of the other London makers.
We don't know how many were made, but they are quite rare now: Leif Sahlqvist's extensive research has only found seven, compared to hundreds of 5½-octave pianos. This is essentially an eighteenth-century instrument.
This is an addition to the seven. At least one of the others has the name on a stuck-on engraved cardboard label (as used e.g. by Thomas Tomkison) and it is possible that the calligraphy on this one is a replacement for that label.
The number 309 fits neatly into this relatively small group, and perhaps gives some idea of how many were originally made.
The attractive S-shaped souind-hole is also seen on the only other example for which we hae pictures. This feature is also seen on contemporary pianos by James (Jacobus) Ball, but it might be going too far to imply that he was the maker.
This piano does need complete restoration, but the good news is that it does not seem to have been 'interfered with' (we have a technical term for that) and so we can see no irreversible damage, and most, possibly all, of the original parts are there.
We should remember that there will never be any more of these historic pianos made, and the opportunity to examine, document, and restore an original unspoiled example is diminishing fast.
The piano is in Bristol; the price is £950. Please contact Adam Etheridge