OK, here's my synthesis of what seems to be the most complete version, compiled from the various sources mentioned above (thanks to Malcolm for the helpful links). You'll see that I fudged a bit and put "never spied the creel" in place of "never twigged the creel" which sounds anachronistically modern to my ears – though that sort of thing can be deceptive: I once heard a piece of slang that I could have sworn came from gangster-era New York, only to learn that it actually originated in Shakespeare's England. Anyway:

PRETTY PEG

When Pretty Peg walked down the street
Some fresh fish for to buy
The wee town clerk followed after her
And he kissed her by and by

With my tiddy right faladiddle daddy
With my tiddy right faladiddle day

Oh how can I get to your chamber, love
And how can I get to your bed
When your daddy goes to sleep at night
With the key lying under his head
Oh go and get a ladder, love
With thirty steps and three
Put a creel all on the top of that
And come down in the lum to me

So he went and got a ladder
Of thirty steps and three
And put it up to the chimney top
And came down in the creel to she

No peace nor ease could the old wife get
With dreams running through her head
I'll lay me life said the gay old wife
There's a boy in our daughter's bed

Up the stairs the old man crept
And into her room did steal
Silence reigned where the daughter slept
And he never spied the creel
My curse attend thee Father
What brought you up so soon
To put me through my evening prayers
And I just lying down

He's gone back to his gay old wife
He's gone back to she
She has the prayer book in her hand
And she's praying for you and me

No peace nor ease could the old wife get
Till she would rise and see
But she came on a stumbling-block
And into the creel went she

Hi I rocked her, ho I rocked her
Didn't I rock her well
For if any old wife begrudge me her daughter
I'd rock her into hell