Where your house is bare stone, brick or render, avoid paints and other coatings. If your house is rendered with stucco, this was done to imitate stone and was therefore normally painted. Ideally use a lime wash, but otherwise choose a modern paint in an appropriate colour. After fresh render is applied, allow one week's drying time for each 6mm thickness of the render. So if the render is 1cm thick, allow the render to dry for at least two weeks.
Georgian stucco was often painted in darker colours than today, but to preserve the unity of a terrace and local area, your local authority or preservation group may recommend a choice of colours. Otherwise go for a cream or a beige, rather than a brilliant white.
Why not use modern wall coatings? This quotation is from the leaflet distributed by a market-leading exterior coating company:
"[Our] process is designed to completely renovate your exterior walls regardless of the type of surface or its condition, and it can be applied all the year round. Problems such as blown rendering, falling pebble-dash, spalling brickwork, damp and porous surfaces, patchy Tyrolean, uneven rough-cast or deteriorated stucco can all be things of the past. [Our] coating - which is applied under high pressure spray by our own skilled specialists - will transform the walls of your home and provide decorative protection and weather proofing that is guaranteed for 15 years against chipping, flaking or peeling. [Our product] will also insulate and repel penetrating damp, and is available in different textures and any colour from the British Standard range.
"[Our product] is 20 times thicker than ordinary paint, and its unique formulation (which blends resins, minerals, titanium, fungicide, fibre-glass and other chemicals) produces a revolutionary breakthrough in exterior protection. [Our] process is approved by local authorities, councils, banks and building societies. It is thoroughly tried and tested with amazing results and has been used and proven on both domestic and commercial properties for many years."
These claims can be true for cavity wall buildings, but for any building with a solid wall the risks of subsequent problems are far greater than the possible benefits.
If walls are in poor condition, these products will not 'solve' the problem, any more than lining paper will 'fix' damaged plaster. The very robustness of these products means that subsequent removal, in the event of difficulties, is difficult and very expensive.
Old buildings do not need "weather proofing' in most UK climates; indeed they depend on breathability in their walls for maintaining their condition.
This section explains the problems you can have with the exterior paint on walls, and how to remedy them.