Only heard this second hand, but it was from a usually reliable ATCO source, that they've only employed 12 atcos to cover a 24 hour/365 day per year operation.
With funding being tighter than a something that's very tight, salaries were well be below the UK average and that most of those recruited were ex mil' who are already making use of their MOD pension to supplement the poor wage.
That said, I understand that efforts are being made to make the salary more attractive.