The sets were delivered in BR engine green with yellow lining above the windows and at waist level. The first sets had no speed whiskers, and the earlier sets appeared with the early type of emblem with the lion sitting atop a wheel. In time small yellow panels were added. At least one car carried a yellow stripe for first class in while in green. Later some cars appeared in the early matt looking blue with small yellow panels and brown underframe and bogies. A few even made it into the corporate rail blue before withdrawal.

In Nov. '01 a survey was done of the liveries carried by 79900, by careful sanding. Feathering the paint showed that the vehicle had been painted at least twice in traffic, (the repaint having lining over lining), green in departmental use (a lighter green, the lining being painted over green then relined), departmental red/blue (with blue solebar?), and finally the replica green which it carried at the time of the survey. The following details were noted:
First Lining: The lining under the cab windows began 3/8" below, and was a 1 3/4 line with black edges just under 1/16". At the sides the top edge of the black met the bottom of the window frames. The top lining is 1" thick, the lower edge meeting the top of the side window frames. It did not have black edges.
Second Lining: The lining under the cab windows started 1/2" below and was a 1 1/4" line with black edges just over 1/16".
Whiskers: these had an 1/8" black edge, and there was one layer of green beneath. There was two further layers of green before the yellow panels were found. 
Yellow Panels: The top of the yellow panels started 5 3/8" below the lower edge of the window frames, the lower edge being 3 1/4" from the bottom of the cab.
Departmental Green: The top of the waist lining was 1/4" below the side windows. It was 1 1/8" thick, with no black edges.
Red/Blue: The two colours were seperated by 5/8" white tape. There was a 2" gap from the bottom of the gutter (below the bottom angle with the rivets in it) to the top of the tape. There was  1/4" gap below the windows to the top edge of the tape. The sides were 4" from the cab doors, the outside of the curves being a 2 1/2" radius.
Replica Green: The roof was light grey, with white domes. The yellow panel was 2' high and 7' wide. This started 3/4" below the waist lining. This lining was 1" wide, and the top edge was 1/4" below the lower edge of the cab windows. It did not have black edges. It was on average 3/8" below the side windows. The location of the yellow diamonds varied between 3 1/4" and 3 1/2" below the windows and 2" and 2 1/4" from the yellow panels. On the yellow panels was '975010" hand painted in black 4" numbers, 5" from the left edge and the tops 1" below the top of the panel. To the left of the yellow panel was handpainted vehicle data. On the No.1 end was:

PRIVATE was hand painted on the cab doors, the top of the 1" letters being 5 1/4" below the window edge. The M79900 itself was also hand painted in 4" figures, the bottom of these being 9 1/2" from the bottom edge. The coaching crests were 4" from the bottom edge of the body and 4" below the bottom edge of the windows. LOAD 15 C^WT DISTRIBUTED was handpainted white centered below the guard's window. The bottom of the 1" writing was 3" from the bottom edge of the body, and the text was 21 1/4" long. The solebar and bogies were black, the bufferbeams red. The top lining was 1/2" thick. On the cab the top of this was 1 1/4" below the lower edge of the gutter, but on the sides it was 5 1/2" below, with a 1 1/2" gap from the bottom edge to the top of the windows.