In the garden by the information centre there was a Small White butterfly, two Large Whites, one Peacock and two Painted Ladies.
I recognised Wall Rue (Asplenium ruta-muraria) on the ruined Abbey walls, as this is very common on walls in Bristol (but not around Bexley). A fellow volunteer identified the other, more prolific, fern here as Black Spleenwort.
Up at the work site the Heather was coming into flower, and will look good generating a purple haze over the next few weeks.
An unusually low-flying Purple Hairstreak settled briefly on a leaf, and there was a solitary male Common Blue.
The son of one of the volunteers found a dead Common Shrew (a species I have to admit I've never seen before), and a few inches away a Vole or young Wood Mouse, down one of the nearby paths. Neither showed signs of obvious injury and it occurred to me later that they may have been dropped out of an owl's nest.
Later on, I saw a Holly Blue in 'Byway 7' (Leather Bottle Lane), now effectively a rear alleyway behind Elstree Gardens, bordering the north side of the wood east of the Abbey. There were also around 20 plants of Greater Celandine here.