This amazing sundial is in the gardens at RHS Rosemoor. The curved lines are to cope with the different height of the sun in the sky at different times of year. There is a line for every 15 minutes. I was there at 12.15 BST.

Notice that there is a scale above it.

The top scale is consulted between winter solstice and summer solstice. The lower scale is for the second half of the year. Not sure why that is. Notice also that the other side of the stone is for the afternoon.