Dave the gnome, you asked what banjo music has to do with mummers... Well, in Philadelphia, Pennsylvania {USA}it has a lot to do with it. I gather from your post that your mummer traditions are different from the Philly ones. So I guess this is another example of USA'ers being different from UK'ers even if we basically speak the same language...

See this excerpt from a website about "STRUT", an award winning movie about the Philadelphia mummers that is now apparently sold as a DVD:

"It lasts all day, a masquerade with banjos, feathers and sneakers spray-painted gold. Sometimes raunchy, other times glamorous. Think burlesque on the street, marchers strutting with a parasol in one hand, a beer in the other.

The day belongs to electricians, longshoremen, plumbers and cops. And the streets rumble under the heels and toes of grandfathers and grandsons busting loose together.
Everyone has worked so hard and waited all year for this. One day that is theirs. This is Philadelphia. Tradition. Competition. Celebration. Welcome to the Mummers Parade!
http://www.strutthemovie.com/#
end of quote

Then there is this passage from the Mummers Museum in Philly:

"Mummer" comes from the Old French momer, to wear a mask; pantomime. It means a masked or costumed merrymaker, especially at a festival (American Heritage Dictionary, 3rd Edition).
Mummery is an old tradition in Philadelphia, and the famous Mummers Parade dates back to pre-Colonial times, resulting from a blend of Swedish, Finnish, Irish, English, German, African-American, and other European heritages. With the Mummers in full swing, New Years is celebrated in Philadelphia as it is nowhere else in the world.
Those who participate in the festivities are sometimes referred to as Shooters and Mummers. A bit of history: In the late 1700's, when the Swedes came to Philadelphia, they brought their custom of visiting friends on the Second Day of Christmas, December 26. Later the period of celebration was extended to include New Years Day. The grandest of celebrations became grander and grander with each new year. Celebrating the New Year was a noisy affair. With most people in those days carrying firearms for protection, many shot in the New Year. Hence the term Shooters.

Today's parades include juried competitions. While firearms are no longer discharged, the revelry is as intense as the rivalry between the various mummer groups, assuring spectators and participants alike a wonderful time.

The Mummers Museum celebrates all that is mummery and New Years Day. Visitors will enjoy unique exhibits featuring the intricate handwork that goes into the elaborate costumes. Everyone can learn to do the renowned "Mummers Strut" to the tune of "O' Dem Golden Slippers," the unofficial Mummers theme song composed by Philadelphian James Bland in 1879.

http://www.fieldtrip.com/pa/53363050.htm

end of quote. Although the passage says that the Mummers are traditionally associated with New Years Day in Philadelphia, I believe the parade is on Thanksgiving dayvsomehow I I am 99% sure that at some point {maybe because of commercial considerations} the Mummers Parade is on Thanksgiving Day.

As a matter of information, James Bland, the composer of "O, dem Golden Slippers was African American, an irony since African Americans were really not at all welcome as Mummers until some date
I'm unsure of, but I don't think it's been 30 years yet.

Here is another excerpt:

"Welcome to the home of the Philadelphia Mummers. If this is your first exposure to mummery, you may be wondering who and what we are. We are entertainers that have strutted every New Year's Day in Philadelphia for over 102 years. We are famous for our elaborate, sequined and feathered costumes. As well as our upbeat music, choreographed dance routines, and of course the mummers strut."
http://www.phillymummers.com/
end of quote.

As to competition: there is a comic division, a string division {mostly banjos}, a fancy division. For a description of the string division, see this quote:

"A central theme dominates music, costumes and presentations of the groups of 48 or more musicians. Plumed and bespangled, they mark time to music, highlighted by the banjo and glockenspiel. Ornately garbed captains join the band in precision drills."
http://www.phillymummers.com/
end of quote

One correction, apparently the Philadelphia Mummers parade is on New Years Day instead on Thanksgiving Day as I had written. I apologize for the mis-statement.

My comparison with this tradition and the New Orleans Mardi Gras Wild Indians was because in both traditions members of competitive groups wear intricate, colorful feather outfits..though these outfits are distinguishable between the two traditions.

Oh, and there does not seem to any mention in these websites of the Philadelphia Mummers "blackening up" . And GUEST,Scoville says that this was not a part of the tradition for his great-great-grandfather..So again we may be talking apples and oranges or at least oranges and tangerines when we are discussing the Philadelphia Mummers and the UK/Europe Mummers.