In the film 'The First Great Train Robbery' what is the name of the piece of music being played by the two women on the pianos while Connery and Sutherland look for the key?

So far, all I've found is the full track listing:

Full Track list:

1. Main Title (2:33)
2. Breakfast In Bed (1:48)
3. No Respectable Gentleman (2:22)
4. Clues (3:53)
5. Rotten Row (2:40)
6. The First Key / Bordello Raid (:51)
7. Kiddie Kaper (2:02)
8. Street Attack / Casing the Station (3:08)
9. Over The Wall (1:57)
10. Night Entry (2:27)
11. Double Wax Job (2:55)
12. The Tombstone (1:11)
13. Departure (:41)
14. The Gold Arrives (2:35)
15. Torn Coat (1:50)
16. End Title (2:57)

http://www.soundtrack.net/album/the-great-train-robbery/ You can listen to each track here and discover the right one (satguru)

This may be it, The Sonata in D major, K. 448 by Mozart.

"The Sonata in D major, K. 448, has been a personal favorite of mine since hearing it many years ago in the Sean Connery film The Great Train Robbery. The music's sense of hijinks perfectly matched the general tone of the film, and a good performance carries along a highly contagious sense of good humor."

Here is a video performance of it, not from the movie itself, but maybe you can tell if it is indeed the piece you're looking for.
http://www.youtube.com/watch?v=myJOl7ia0gg

You might also want to try Gordon Langford's "Marche Humoresque from Suite for Piano Duet" by Gordon Langford.
"...Worked as orchestrator for several West End musical shows, plus orchestrations for many American movies such as 'Raiders of the Lost Ark', 'Superman II', 'First Great Train Robbery', 'Clash of the Titans', 'Return to Oz', 'Tribute' etc."
Suite for Piano Duet - an arrangement of Divertimento for Saxophone Quartet(by Gordon Langford).

https://en.wikipedia.org/wiki/Gordon_Langford