Mirrors on the highway
New mirrors are not permitted on the highway. Mirrors are not covered by regulation, and until June 2013 every single mirror required special authorisation by the Department for Transport, but they no longer accept any applications for mirrors.
New mirrors are not permitted because of concerns with road safety. Experience shows that rather than improving safety, a mirror could increase safety risks, particularly reflected lights.
If you are concerned about the visibility from your driveway you are advised to consider other measures that might improve sight lines, for example, cutting back vegetation or realigning boundary fences.