Yes, indeed, it was all about politics, as this extract from Hansard in 1962 reveals:
MILITARY TRANSPORT AIRCRAFT (Hansard, 4 April 1962)
I remember the Martlesham Heath Herald/748 rough field trials and the high-altitude paratrooper trials, and worked on the Heralds involved. All successful for HP but of no avail. The politicians had made their minds up.