I'm certainly not tall enough to claim "special needs", but would gladly pay £15 for more legroom on any sector above about 2 hours. Isn't this the whole point of the Premium Economy seats?
Compared to the extra you pay for these, £15 is a bargain. With regards to the safety aspects, yes I agree you shouldn't have a mother & toddler there, but has anyone added up all the time spent listening to safety briefings v the number of lives they've actually saved? The irony for me is that the seemingly most dangerous flight I've ever taken - to Saba - had virtually no safety briefing.