Melbourne House dates from 1857, and is now the headquarters of a telecommunications company. It was built by the evangelist 'Prophet' John Wroe who founded the Christian Israelite Church. A controversial character, Wroe moved to Australia where he died and where the church is still active.
The cache is across the road from Melbourne House between a largely fallen-down wall and a wire fence, at ground level close to the wall. You will need to move one stone to find the box, but it is not in the remains of the wall and the stone you need to move is not part of the wall - though presumably like all the stones nearby it once was. You can park close by, but be aware that this normally quiet road can become a rat run with people cutting through to the motorway at morning and evening rush hour and school start and finish times.
Sorry, but this cache is not accessible by a wheelchair; the final five metres or so are simply too rough. Congratulations to Clan-Wallace on FTF.