I'm looking out for 'The Oldest...', but from the same album (with singular guitar accompaniment by Chris Newman) is this one:

BREATHALYSED (Tune: Yesterday [The Beatles])

Fred Wedlock

Breathalysed.
Crystals turning green before my eyes.
I turn yellow as I realise
That I have just been breathalysed.

Suddenly.
There's a policeman looking down at me.
I'd like to thump him, but he's six-foot-three
And I should like to stay alive.

CHORUS
I did something wrong, and I know it was a beaut.
When he pulled me in, and I parked upon his foot.
So, gently

I was sick.
When they took me down the local Nick
I never saw a Sergeant move so quick,
But not so quick, as I was sick

CHORUS
They said, "We want your blood to test for alcohol"
"Go away", I said, "and get knotted Dracula...
Ahhh...Ahhh, Ahhh"

Analysed.
Five hundred milligrams per hundred ml.
Now they reckon I'm a walking still,
And I shall soon be penalised.

Yesterday.
All my troubles seemed so far away.
Now I'll take back those rude things I said
Nice big red bus please come my way.

B.