Well, since the song was written for Shirley Collins, I guess one could consider the Shirley Collins version to be definitive - but I think I like several word choices in later versions more - even Shirley Collins made changes in later performances.

Here's the recording from the Shirley Collins box set Within Sound (2002):

https://www.youtube.com/watch?v=FJjj9zCMOwc

And here's my transcription of this recording:

WHITSUN DANCE
(words by Austin John Marshall, as recorded by Shirley Collins)

It's fifty-one springtimes since she was a bride,
But still you may see her at each Whitsuntide
In a dress of white linen and ribbons of green,
As green as her memories of loving.

The feet that were nimble tread carefully now,
As gentle a measure as age do allow,
Through groves of white blossom(?), by fields of young corn,
Where once she was pledged to her true love.

The fields they are empty, the hedges grow free--
No young men to tend them, or pastures go see
They've gone where the forest of oak trees before(?)
Has(?) gone to be wasted in battle.

Down from their green farmlands and from their loved ones
Marched husbands and fathers and brothers and sons.
There's a fine roll of honor where the Maypole once was,
And the ladies are dancing at Whitsun.

There's a row of straight houses in these latter days
All covering the downs where the sheep used to graze.
There's a field of red roses (??), a wreath from the Queen
But the ladies remember at Whitsun,
And the ladies are(?) dancing at Whitsun.


Some of these words are hard to understand, but I did the best I could and put question marks where I had trouble. The "red roses" surprised me, but that's what I hear.

Reinhard's Mainly Norfolk says this was a previously unreleased 1968 demo, so maybe it was polished up a bit in later recordings.

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There's another Shirley Collins recording of the song here:

https://www.youtube.com/watch?v=yiv6FslfdFI

The lyrics in this version have poppies and several other differences from the demo recording.

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Please note the post above (click) from Desert Dancer for a 1982 version of the lyrics from the songwriter himself, Austin John Marshall.