Land around a mysterious cavern underneath Blackheath could soon be under investigation. Parkman's, the surveyors who investigated a six-foot-wide crater that appeared in the A2 at Blackheath Hill last April has said further checks on land stability in the area are needed. Decisions on their report were to be made by Greenwich council last night. But the council, which would apply for a grant from English Partnerships to cover the costs of the investigation, is not yet sure how much it will cost. The collapse of the A2 into chalk pits after subsoil washed away triggered traffic chaos, hundreds of...