My preferred method is to weight votes according to age: voters below, say, 30 would receive a more heavily weighted vote, voters 30 to 60 would get a less weighted vote, and those over 60 would retain their current single vote. For argument’s sake, you could multiply the vote of under-30s by 1.3 and that of 30- to 60-year-olds by 1.1. People’s ballot papers could be distinguished by colour – under-30s get blue, 30s to 60s green and oldies red – to make counting easier on election night.