New window in 2 foot thick stone wall house

Okay, seeing as none of our resident restoration experts want to answer this one here's my halpennys worth. To change the window you will have to conform to building regs/FENSA. I suspect there is no lintel or an inadequate sized one at the moment. This job will invole you inserting a lintel above the opening with bearings (resting points) on the wall at a minimum of 150mm each side. It has to be the right type of lintel for the type of wall and must be suitable in design to bear the weight of the stone above. This can be calculated in kilo newtons by most structural engineers. That's the reason you have small windows, it wasn't the done thing in those days and you could get away with the timber window propping up the bricks or the stone taking the stress points. You can even today get away with a 500mm opening without support. In olden days if you wanted a big window you made it arched instead of using something as primitive as a lintel. Once that is achieved you can pretty much pop in any window you fancy but if your in a conservation area you may need consent anyway (planning permission). For that age of house it would be nice for the window to match the current architectural style of the existing and be made from hardwood that should be oiled or painted in linseed paint. If you go for softwood that would need a plastic modern paint. The building reg charge for the lintel is separate to the charge for the windows. Hope this gives you an idea of what's involved. Find a local conservation builder who knows.