Just a bit of info which I hope might be of interest.
I have never found any reference to these commercials, although my sister can also remember them

1.) I can remember a commercial from the 50s by the Caley Chocolate Co.
(https://shinealightproject.wordpress.com/2013/10/08/chocs-away-norwichs-history-of-chocolate-making/ )
for a product they called “Cuba”, which isn’t mentioned in the above article.

The weird thing is that I can remember part of the song.
As I remember it, there were pirates walking about, manfully eating “Cuba” (think of it as very small, square, plain chocolate “Bounty” bars”)
and part of the words were –
“…big buccaneers shed tears for “Cuba”,
Tender chocolate squares (?) of “Cuba”,
Coconut treasure, my what pleasure,
Sixpence price of “Cuba”

Followed by the final lines –
“Yo Ho for Caley’s “Cuba”,
Sixpence price of “Cuba”!”

2.) There was an advert in the 50s for “Shippam’s Paste”, with a shrimp as a rock and roll singer.

Part of the words, towards the end of the commercial, were
“ … I’m a tea-time rock ’n rolling fool,
But Shippam’s paste is really cool,
Something, something, salmon and shrimp,
Something, something, something, something,
Insist on Shippam’s,
It’s the paste you want for tea,
(repeat for the finale) It’s the paste - pause – you - pause - want- pause – for - pause - Teeeeeeaaaaa!

Shrimp does an Elvis Presley collapse in front of the microphone, and a voice from the background shouts out, referring to tea-time, “It’s ready, Freddy!”

3.) There was an advert for “Magic” margarine, where a rabbit danced around to the music of Tchaikovsky’s “Danse des Mirlitons” from the “Nutcracker Suite”, so pre-dating “Everyone’s a fruit and nut case”
The tag line was, with the rabbit walking along, –
"Treat yourself to bread and “Magic”,
After all, you do deserve the best …”
However, the rabbit never got to complete it, shouting out the last word, “best” as he fell of a ladder, into a swimming pool, etc.

As I said, I hope that this is of some interest to you.
Best regards
Geoff Margetts, Germany