No, they're standard (darker) wagon grey, but covered in a patina of cement dust. Same colour as the brake van - BUT - the sun is shining on them and that also makes them look a bit lighter.
Up close, they did not look that light at all. Very soon after, they started painting the bodies orange, though the chassis would remain grey for another generation until they started painting the "bubble" bit cream - and THEN they painted the chassis black - a rare thing!