Irritating. The Robert Dyas jingle is firmly embedded in my head and won't go away.
It's clever music... Ro-bert Dy-as, Ro-bert Dy-as, all played on a dingly thing (there are no lyrics really, you just imagine the shop name along with the music) that's slightly Christmassy without offending other times of year.
I used to teach my students about that, using the theme music from that old TV series The Sweeney as an example:
The Sween-ey, The Swee-ney, da da da da-da da da da da
Time to rehearse my Chefs songs, silently miming and getting the words just as wrong as I do when you can hear them!