Sorry, for picking up this thread a bit late, but I was out with the organ at the weekend.
The Mortier orchestrion shown in the YouTube clip was indeed the one owned by previously owned by Walkers of Ashbourne. Originally imported by Charles Hart of St Albans from Oscar Grymonprez, by 1966 it had been sold to Alan Barber, who in turn sold it to Walkers. Work was carried out on the organ in 1982/3 by Andrew Pilmer and his father and a bandmaster was added. The organ was a bit puzzling in that the front was very much in the style of the Beersel Mortier, see
http://www.dansorgels.nl/Mortier/mortier84torchbeersel.htm, albeit with the centre panels removed and heavily repainted. It was stated that the organ was built in 1928 and this would correspond to a front of this style. The mechanism, however, appeared to be that of a much later organ, with asymmetrical pipework, rather than the symmetrical ranks found in Mortier orchestrions of the period.
On 16th May 1998 the Walker family held a public auction of various items, including the organ and lorry, which sold for £25,500 plus buyers premium. It went to a private buyer in the Yorkshire area. Has anyone seen or heard of it since?
Regards,
Peter