I sent this poor photo to British bug to confirm the ID and it has been confirmed as a Asiraca clavicornis.
An unmistakeable species which was formerly more widespread in southern Britain but is now restricted mainly to the London area and Thames estuary, where it can be locally frequent in rough grasslands and wastelands. The reasons for this apparent decline are not clear; continuing records are important.
The extraordinary antennae and expanded leaf-like front legs are the most striking identification features.
Adult: All year
Length 3-4 mm
How cool is that , but if i knew it was rare I would have taken more photos of better quality