2130martin,
Hello !
Without knowing your land + circumstances etc, like public and animal access etc,
well presented traps, either fenn + BMIs bodygrips in cubby tunnels ( not where they are red squirrels ) or live capture (especially where red squirrels maybe present ) will give you coverage over 24hrs ish, until set off. I use either corn maize (15kg bag costs only £7.50 ) and peanut butter. I check traps twice a day, to ensure they are working 100%.
I also made custom fenn boxes, painted green and screwed them high up in trees, away from human access ( unless they happen to carry a telescopic ladder around with them ! )
Drey poking in conjunction with a few shot gunners lined up or air rifle shooting can be good, if you have the time, but trapping is better overall, as the traps are working whilst you are not there. Grey squirrels are greedy beggars and can't resist well presented free food !!
Cull greys a couple of times a year, if you can, to keep the numbers down and break up the breeding cycle ( squirrels can breed twice a year )
Depending how many traps you put down, it can be time consuming, but very rewarding, when the grey numbers are finally reduced, resulting in more feed to keep your pheasants around and if you eat sqirrels, free food for you !
I noticed your location, it's a bit too far from me, or else i would have be willing to show / lend my set ups / equipment.
Google squirrel control and there are some very good websites to visit for ideas etc.
Fenns and Bodygrip traps can cause serious injury, so please use them with care!
WMA or FourteenAcre are good places to buy traps from.
Good Luck with your quest.