Hanging large heavy mirror to Edwardian wall?

If your fixing to a solid wall, ie brick/block then I would suggest using brown plugs and 7.5mm masonry bit. If its a stud wall, and hollow behind you can use plasterboard fixings which self drill into the plaster board and normally come with the scews, they come in plastic or metal, I would always use the metal ones. As we dont know the weight of your mirror, and it is heavy then myself I wouldnt trust the board fixings, I would try to locate the upright studs, find two timbers, carefully cut out a section of board, and fix a piece of say 50mm x 50mm timber to the required height, you then have a good solid fixing. If you have cut your piece of board out nice and neat, then you can screw this back over the timber and skim back over, remember to set your timber back far enough to allow for the timber, board and skim.

If your wall is a masonary wall, then a standard raw plug should ensure a secure enough fixing, use a masonary drill bit and set the drill to hammerl. If however the wall is lathe and plaster, you are going to encounter real difficulties in getting a secure fixing, especially if the mirror is large and heavy. Does the room have a picture rail you could hang it from? Is the mirror framed? If not then mirror adhesive is very good, apply on back of mirror, position where required, support mirror underneath until adhesive has cured. If your really unsure about getting a good fixing, get somebody in to take a look so that they can advise you about the best solution.

If your not sure about the wall weather its solid ie brick and plaster or a stud wall(hollow) then you need to drill a small hole to find out.Its likely to be a solid wall and suitable anchore fixings should be used. all fixings will have details of their sutability for a variety of wall types written on the packet. A good hammer drill is a must for solid walls as is the right drill bits. In all honesty if your in doubt contact a good handyman and get the job done right first time

If you have not got the tools you would be better to post a job on this site and let a tradesperson quote you ,regards Terry.