In today’s Times profile of Ken Bruce he says:
“When we meet he has been listening to his “big and bright” new GHR new jingles.“I always like to have opening jingles in three different keys so they will match the first song as closely as possible. You’ll notice it if you’ve got perfect pitch, and I don’t have perfect pitch or anything close to it, but if it sounds right, then you’re happier, and if there’s a jar, as you go from jingle to song, it just makes you feel slightly uncomfortable, although most people can’t say why”
https://www.thetimes.co.uk/article/ken-bruce-on-leaving-the-bbc-i-was-annoyed-i-thought-i-m-not-being-difficult-nf7kn6l7j