This will be of no help, but Bert was a feature in the young Ez’s household too. Other regulars included: James Last, The Ted Heath Orchestra, The Peddlars and Glenn Miller.
I discovered this suggestion by accident. The original suggestion was peanut butter (which apparently works) but I didn’t have any, so used some tahini we had in the cupboard (basically, very similar to PB in my mind in terms of texture/components). I had another sticker issue later and as tahini was quite messy (it’s one of those jars that seems to live in the store cupboard for ever) and reasoned that it was the oil that was the main factor; ta da!