This guys a dealer, and the machine has both chucks and steadies. Good machines are expensive.
If you click on his other items he has a very clean looking M250
I think I saw that m250 when I was looking for one, have you seen the one RDGtools are selling? very nice and long bed but £7k

https://www.rdgtools.co.uk/acatalog/Harrison-M250-Long-bed-harr250.html