I believe the song was written by Mick Softley and recorded by Donovan in 1972. I’m sure that when he wrote it he never thought it would seem dated, especially only about thirty-odd years later – after all, tyrannical employers trying to enslave workers have been around since time began. How about:-

“He asked me how many jobs I'd had before.
He nearly had a heart attack when I answered, four.
Four jobs in twenty years, oh, this can never be
We only take on men who work until they die.

Chorus:
“ “Here's your gold watch and the shackles for your chain
And your piece of paper to say you left here sane.
And if you've a son who wants a good career
Just get him to sign on the dotted line and work for fifty years.”

How things like “flexible working”, “zero-hours contracts” etc. have changed Britain since then, with a “job for life” now regarded like gold dust to some people. Perhaps a more updated version would be:-

“He asked me how many jobs I'd had before.
He nearly had a heart attack when I answered, four.
Four jobs in twenty years! Oh, that will never do
We have short-term contracts then it’s down the road for you

Chorus:
“Forget your gold watch hanging from its chain
Here’s a six-month contract then you’re on the dole again
And if you've a son who wants a good career
We’ll give him a job on minimum wage till later in the year”