Ancient sundial in church porch

Today I visited a beautiful little church just off the A1 in the very north of Hertfordshire. Caldecote was devastated by the plague but the church has somehow survived through the years, virtually unchanged and therefore rather simple and special. There's no heating or lighting and virtually no parish to maintain it so the Friends of friendless churches look after it and support it. It's opened a few times a year and this occasion was for a fuchsia festival. I've photographed the church before but today I wanted to play with my macro lens and the flowers. However this shot stood out as something rare and unusual. I have been before but I had not noticed this sundial in the south porch bench. There is only one other known horizontal dial in the country ( at Lolworth, Cambridgeshire). What appears to be the hole drilled in the centre point for the insertion of the gnomon has been filled in. There are 3 mysterious incised outlines in the shape of the human foot, one beside the dial and a pair further north, all facing inwards along the same bench. If there is a purpose to them, linked to the dial or otherwise it is a puzzle. Further investigation is in progress.
A further survey discovered 2 further vertical dials to the west of the south porch. These possibly took over from the bench dial as the sun's position moved westwards. See www.caldecotechurchfriends.org.uk for further information on this lovely little church and village.