They're nor particularly rare but they have some value depending of course on condition. I'm afraid I can't help you with that. Here's a link to a recent thread where it seems there are several still knocking around in the Essex area. Note that the one in the wood has not been considered for preservation, perhaps because of this commonality. Obviously on looking at the condition of yours it would be toward the low - mid range I would think. Sorry I can't be more precise.
'I do not think we can hope for any better thing now.
We shall stick it out to the end, but we are getting weaker of course, and the end cannot be far.
It seems a pity, but I do not think I can write more. R. SCOTT.
Last Entry - For God's sake look after our people.'
In memory of Capt. Robert Falcon Scott, Edward Wilson, Henry Bowers, Lawrence Oates and Edgar Evans. South Pole Expedition, 30th March 1912.
not that rare,theres still a few lying about.
Kent Battle of Brittain has a good example.