Epiphytic polypody

I've been exploring some neglected woodland fragments in North Buckinghamshire as part of a project to work with landowners to restore some of the glory of the ancient Whaddon Chase hunting forest. I was pleased in one patch, well off the beaten track, to find some ancient woodland indicator plants and this superb Polypody Fern growing on a very old hawthorn tree. This will perhaps seem quite commonplace to some of you more to the west and north of me, but it is quite scarce in this area. Nearby were some lovely large oak trees that deserve further investigation for fungi and saproxylic invertebrates.