I did enquire once about a place I was thinking of buying.

It is a good idea to use an architect/agent who has experience of listed buildings and is not going to specify a B&Q conservatory.

The presumption will be against the granting of permission.

Of course the standard waivers in the general development order are not applicable.

It is likely to be helpful if you can produce evidence that there has previously been an outhouse/conservatory/orangery/gazebo preferably where you want one but otherwise at least attached to the building.

The one I was after was Murrells, in Gravesend, allegedly the oldest continuously inhabited dwellinghouse in Gravesend. The incised date on it of 1687 is almost certainly the date of a renovation or extension, as the roof interior shows the remains of a rather nice Kingpost and Queenpost roof.

Unfortunately we could not sell our own house fast enough - well, I say "unfortunately" but there was a huge amount to be done.

A Victorian extension appeared to have a full-height but 4.5 inch single brick end wall that was badly bowed. The main roof was of dubious stability with broken internal timbers. There was an agricultural extension to the rear largely of breezeblock with a catslide roof. The oak timberframe appeared to be held together mostly with Victorian 3/8 inch mild steel angle brackets and huge woodscrews so the original timberframe interlocks were probably no longer sound. Previous owner had fixed things up his own way with modern cement that was likely to result in differential stresses, and had put "DiY" quality internal partitioning in to divide bedrooms. The cellar appeared once to have been a cow-byre as the mangers were still on the wall, but the floor above was held up by a modern brick pillar in the middle and the roof height was about 5 feet, so there must have been infill in part, and the animal entrance had been filled in - probably under the breezeblock bits, where now ran a rats nest of heating pipes for a very elderly heating system that had two separate boilers, one gas and one oil.

The main chimney was no longer gas-tight and the fireplace in the Victorian extension had been closed off.

The Aga had been disconnected and a fishtank installed over it, probably between the wars.

Oh yes, and the waterproofing from underground damp appeared to be a clay bed that now had holes through it for the central heating pipes.

God how I wanted that house, but it was not going to be a sensible move!