I see over at Madness HQ in the brilliant section on the history of
the band it states (of the the 2 Tone Tour):
"The tour has a running order of The Selecter being the first band on
with Madness next on the bill and The Specials closing off the night."
http://www.madness.co.uk/1979_part_02.html
This is at odds with the often told tale that the tour had a rotating
headline.