Jonathan posted this on the British RCM&E website yesterday. It looks like some of the single cylinder engines are available again.
"you are a week late STF. A batch of 5 80's have been and gone, replaced by the 4 you see now and with another batch already started. The 4 180's i had a week ago have gone but more are on the way. So, if you need an engine now they are there. if you dont need one and are only buying it for 'stock' then shoo! go 'way!!
I am building engines, they will be available, there is no need to panic buy.
"