Interesting - the coin was listed for sale as 1386 class 2b, 1385 is the same value in Spink - although it all dependent on condition F = £20 GBP VF = £60 GBP. Its good to have a minting date - thank you.
After looking again, now I am having second thoughts about saying definitively that it's 2a. I think your listing is correct saying 2b. The neck on the portrait I think justifies the 2b. My apologies!
Thanks again - the neck area of the portrait is not the best to see the finer details to aid identification.
Yea...I think I just jumped the gun on the sub-class. Its very close. The major difference between the class 2a and 2b is the crown. Class 2a crown has a left leaf of the central fleur that is broken. Your example certainly looks that way to me. However, that could just be a bad strike and the neck and drapery of the King are of that of 2b.
You really don't need to do anything special to the coin. Just keep it in a dry, clean environment and it will be fine. It survived 700+ years underground, it should be fine in your coin cabinet