Lichen calligraphy in Ayot St. Lawrence

Ayot St. Lawrence is a village in Hertfordshire in England that attracts certain number of visitors because this is where Bernard Shaw lived and his house is now a museum. I, however, was more interested in some tombstones in a parish graveyard, especially those where lichens had a special effect on calligraphy. The tombstones aren't very old, both reproduced here are from the mid nineteenth century. I suppose this is the best age for the lichen effect, older stones are more weathered and usually hardly legible (unless renovated), newer ones are perhaps still looked after and too clean. Both tombstones are of the members of Pinnock family.