Hi Brian, in L.B.S.C.'s notes he says the big sister was in Royal Blue and lined out in black and red, and the inside of the cab was a kind of buff, the inside of the frames being grey while the outside were black.The wheels were blue and the tyres black The smoke-box, chimney, running boards, tender top and cab roof were all black. The coupling-rod flutes and buffer beams were red along with the guard irons.
Below is a link that may help you also.
**LINK**
Below is a photo of GER E4 (T26) No. 490 that I took at Bressingham Steam Museum back in the mid 90's, it doesn't give the colour true justice but should give you a reasonable idea. I believe most of the GER engines of this period had much the same livery.
There are some close ups and one of the inside of the cab in my GER E4 (T26) No. 490 album.
Regards Nick.
Edited By Nicholas Farr on 05/06/2012 17:46:50