There are three species of landfowl (or gamebirds) in this area:
Pheasant is the one most often seen all over the area, and there is a male currently residing in Mercers Wood.
Pheasants are especially common on farmland outside of the town, especially after breeders have released young birds into the wild. While walking along the riverside at Gainsborough they can often be heard crowing from the other side of the river.
Pheasant (male and female) (pictures from Wikipedia)
There are two species of partridge in Britain, and both can be found in the Gainsborough area.
Red-legged Partridges are the one usually seen (or head crowing).
A good place to find them is along Field Lane beyond Morton. There were 26 of them there on Dec 28th 2017.
They can occasionally be heard from Gainsborough’s riverside crowing from the opposite side.
Red-legged Partridge (picture from Wikipedia)
Grey Partridges are strictly countryside birds, and can sometimes be seen on the riverside between Morton and Walkerith, or along Field Lane. Winter is the best time to see them when they form small covies, and there isn’t much cover for them to hide in.
Groups are usually small, although I did see 18 in a field next to Field Lane on Nov 1st 2017. And there was a large group of about 30 at Beckingham Marsh on Nov 10th 2017.
There were two Grey Partridges in Morton Cemetery on May 12th 2018, and two on the riverside by Mercers Wood on Jun 14th 2019.
Grey Partridge (picture from Wikipedia)