Mosaic.

This has been in place for 10 years but I've only just noticed it now that some of the tiles are getting lost. I had no idea what it was about until Mr. Google told me:

One of the more interesting historical memorials in Garston is the  commemorative mosaic remembering the Toxteth born astronomer Jeremiah Horrocks and his 1639 predictions about the transit of Venus across the Sun. Horrocks Avenue, Garston is named after Jeremiah Horrocks who lived at the Lower Lodge on the Toxteth & Garston border in Otterspool. The stream that went through Otterpool Park forming the boundary between the two townships.