There's still instinctive tendency to talk as if this was a presidential style national vote. It's not, it's hundreds of local polls, and in different places different choices are appropriate.

As eliza pointed out, Scarborough, which is where Norma and Martin are voting, is a seat where there's every possibility that not voting Labour puts the Tory in - and with a Tory party adopting a racist anti-traveller policy, that isn't something they are prepared to go along with.

In other seats it's a different story, and a different choice would make sense.