To continue to deny any element of minstrelsy in the border dance tradition does seem to fly in the face of the evidence.

From Andy Anderson's comprehensive account of border morris ,a href="http://dialspace.dial.pipex.com/town/avenue/pd49/">here,:

One tune that was used regularly is 'Not for Joe', or 'Om Si the Gom Si'. This started life as a 'nigger minstrel' song and either took its folk name from, or gave the name to, a particular style of Border Morris Dancing. Some of the versions of the words for this song would be considered mildly obscene even today and it is not surprising that the collectors did not print them, although they often recorded them in manuscript.

There's also this from E.C.Cawte's manuscript of collecting trip in Ludlow in May 1957:

Bill Fury (58, Hollybush Milkbar)
Boys aged c.12-7. Wearing women's clothes and with black faces, used to go about on Boxing Day doing a "Nigger Dance" or "Morris Dance". (I question the latter title, because when I first asked him about morris he knew nothing of a local team). Dance consisted of turning each other with linked arms, and hitting sticks together. Had a musician and sang songs while dancing, the only one he remembered was "So Early in the Morning".
His father started a team of "Nigger Minstrels" with his sons, for 6 years up to 1920, "to show the boys how to do it". Included hit songs, and step dancing, and a dance in which they "went round, and hit their sticks at the end, one held his stick out, and then they changed over". This also was done on Boxing Day. Wore small top hats, big bow ties, tail coats, and striped clown's trousers, and father wore a mortar board. Black faces. Had concertina, (father), bones, tambourine, and guitar (B.F.)

And in Aston-on-Clun the same month:

Ivor Meredith (est. 30) & village blacksmith (est.45)
No knowledge of morris dancing. On mention of niggering at once said they knew it very well. Continued until 1938, at Christmas. Last leader was Arthur Canty, "a proper fool he was... you know, a clever fool". (I.M.)
Went about in fancy clothes, with black faces, playing fiddle melodeon, and mouth organ, singing songs and carols. They jigged about a bit, but there was no dance, and no stick hitting.

And in Onibury:

Onibury, 27.v.57
Man of about 70
There have been no resident morris dancers for the last 60 years. Remembered men going niggering at Christmas; black faces, fancy dress, someone played melodeon, and they sang songs. Someone carried 2 sticks (on direct question), but neither direct question nor direct suggestion would elicit anything resembling the 'Westwood' performance.

And these are the words for 'Not for Joe':
NOT FOR JOE

Humdidi, dumdidi, toorah loorah,
Humdidi, dumdidi, toorah ley,
Humdidi, dumdidi, toorah loorah,
Play it on my old banjo.

1. We had a little nigger,
And he grew no bigger,
So we put him in the Wild West Show.
He fell through a winder,
And he bloke his little finger,
And he couldn't play his old banjo.

Toorah loorah lilo,
Toorah loorah lilo,
Toorah loorah lilo,
Play it on my old banjo.

Humdidi, dumdidi, toorah loorah,
Humdidi, dumdidi, toorah ley,
Humdidi, dumdidi, toorah loorah,
Play it on my old banjo.

2. My uncle Billy,
Had a ten foot willie,
And he showed it to the girl next door.
She thought it was a snake,
So she hit it with a rake,
And now it's only five foot four!

Toorah loorah lilo,
Toorah loorah lilo,
Toorah loorah lilo,
Play it on my old banjo.

Humdidi, dumdidi, toorah loorah,
Humdidi, dumdidi, toorah ley,
Humdidi, dumdidi, toorah loorah,
Play it on my old banjo.