Great photo! From the size of the leg, it could perhaps be a culled invasive muntjac? I recently found out elsewhere on the forum that Colchester do that to feed some of their large carnivores and reptiles, supplying the food from local gamekeepers.
I'm not sure, it might be. In general in much of the UK deer of multiple species need to be culled in substantial numbers to keep populations in check especially where tree regeneration is desired.
@Kalaw It's fairly common to see Muntjac in the enclosures at Hamerton, most identifiable as the vultures get a head. I've seen what I thought were CWD bits too, but Muntjac more.
Muntjac are of course subject to a fully open season in shooting terms (with advice indeed to shoot heavily pregnant does in the deer's breeding season to avoid leaving abandoned fawns) and the carcasses go for a low price per kilo in themselves, though stalking estates / shoots charge clients a decent amount to shoot them (and other wild deer, CWD, Roe, Fallow in this region and then Sika in pockets and Red further up North). I don't shoot them myself (well only with a camera!) but spend time at places that do. With no natural predators the population does tend to grow. And probably better shot by someone with some skill than gone under a car, on balance I guess.
Hamerton appear to have a steady supply.
Whipsnade get some in too, with a full leg being carried around by the male wolverine on my last but one visit. Though I thought that was Roe.
