This can be found in a church alongside the road to Burwick pier where the short sea ferry crossings take place in the tourist season). It is now in a back room at the church, and the key can be had from the lady who runs the local P.O. As this is on the 1:25,000 but unsignposted it is probably best to enquire at the Tomb of the Eagles in order to avoid disappointment outside of its limited post office hours.