The Watersons' version is taken from a music sheet in the possession of Frank Kidson, giving J. Perkins as the composer of the song. He apparently lived near Holmfirth and was supposedly so musical he called one of his sons Mendelssohn Perkins. I've looked up J. Perkinses and M. Perkinses in Yorkshire in both the 1881 and 1901 censuses and there isn't anybody who fits the bill and certainly no Mendelsson Perkins.

Kidson thought that J. Perkins had not really written the song at all, merely gained fame by arranging it for four voices, and that the song was far older than J. Perkins. He is probably right as his music sheet, with J. Perkins as author, is almost certainly No. 10 from Wood's Collection of Glees. Here's the British Library catalogue entry.

Author Perkins, J.
Title Pretty Flowers ... Song and Chorus known as the Holmfirth Anthem.
year   [1896]
descr. fol.
Series ( Wood and Sons. Wood's Collection of Glees, etc. No. 10)

The song occurs in various forms outside Yorkshire. Vaughan Williams noted a version in Hampshire and F. Keel foud a variant in Surrey in 1913.

The Bodleian Library Broadside Collection has a single version of this song ... see Bodlein Broadside Version. Being published in a songster, the song is almost certainly earlier than the date of 1850 given and the version shows signs of having been summarised from another song and incompletely recorded (e.g. "Darling" or something similar for "Evening" would make verse 2 a bit more sensible). Details are as follows.

Sheet Title: The Singer's Album
Printer:    Jacques, G. (Manchester)
Date:       c.1850
Imprint:    Printed, and Sold Wholesale and Retail, by G, Jacques, Oldham Road Library, Manchester
Illus. Ballads on sheet: 11 (the song is No. 8)
Note: Stamped: Bodleian Library, Percy Manning Collection, 1917. Large format
   
Copies: Firth b.28(36)

Here's a transcript.

ABROAD FOR PLEASURE

Abroad for pleasure as I was walking,
It was one summer's evening clear,
And there I beheld a most beautiful damsel,
Lamenting for her shepherd dear,

Dearest evening when shall I behold thee
Evermore the lad that I adore,
Wilt thou go fight with the French or Spaniards?
Shall I ever see thee more?

No more to yonder green banks will I take thee
With pleasure for to rest thyself,
And view yon lands, but I will take you
To yon green mountain, where the pretty flowers grow.

:-)
Ian