Built by Bruce Mills UK.
http://brucemills.webs.com/20inchf4telescope.htm
Awhile ago I bought a 20" f4 Zambuto off an Astromart auction on a whim, as you do. When to my surprise my bid actually won I then had to decide what scope I was going to put it in. Doing a bit of googling I came across Bruce Mills scope and long story short he offered to sell it to me.