My understanding is that last year's dividend was £72m, of which £30m was a one-off special dividend resulting from the refinancing that was done at the time of the STN deal. The 'normal' dividend was £42m, up from £20m the previous year.
Historically the dividends have been relatively low compared with the potential value of the airport, leading to suggestions that the local authorities would be better off selling the airport and investing the proceeds elsewhere. But with a new shareholder on board at MAG, a new more generous dividend policy seems to have been adopted. The new shareholder will certainly want a better cash return on its investment than what the local authorities have been getting these past years!