Hi Iain
The bird does look like a Kalij Pheasant, a common inhabitant of the Himalyas, though the apparent extensive white on the back might point to some sort of hybrid, perhaps with Silver Pheasant, such birds can sometimes be very difficult to tell.
A fine specimen though!
I suspect that species such as Kalij (and Silver Pheasant, plus other pheasant species) are quite common in captivity as they are quite spectacular birds. It is difficult to be certain of the 'purity' of the bird in your photo, hence my mention of the hybrid possibility, and sometimes in can be difficult to ascertain without very close inspection
Feel free to use the comments elsewhere and a call to the country park would perhaps result in the origin of the bird coming to light.
Best wishes
Russell. BirdGuides