Since Jane didn't like my suggestion of two monoliths and a Silbury mound representing HA, how about a logo in which an "italicy" sort of H is leaning against a bold upright letter A. Each could be in it's own colour (let the arty types choose those) and the cross bars would form a continuous line through the middle that could have "Heritage Action" on it. The imagery is meant to suggest that our heritage needs the support of our action.