Certainly STN has the required catchment to support First Business & Premium which has been well proven.
The major problem for STN is the enduring legacy (at present) of "Fortress Heathrow" & Alliance "market cartels" furthering their own ends with lack of customer thinking/service & imagination.
Another clue in the JBU song & dance routine with award of possible temporary usage waiver slots is that both Bamboo & Westjet have also been awarded slots at LHR this Summer.