Well I know what I would have done if I’d found it! Best not for a public forum though 😀

The email received seems to be saying as much as “Please pick it up and put it on your mantlepiece.” but with a little more subtlety.

Let’s face it nobody takes something like that and dumps it in the woods unless they don’t want it or its nicked.

Tell the police you have found something of significant value in the woods.

Contact the land owner as the obvious potential owner.

If no one claims it then it’s yours.

… According to Ask the Police, the UK police FAQ database, if you find something you should liaise with your local station. You may agree to hold on to the property on the understanding that if the owner comes forward you must relinquish it, or you can hand it in at your local police station. If you choose to hand it in you will be given the form that entitles you to collect it after 28 days.

https://www.theguardian.com/money/blog/2012/jul/02/finders-keep-regardless-value