Not entirely sure this is a political decision. The medical profession is urging that single doses be given, but the GPS who have to go through the administrative work of contacting and explaining and facing their patients would, understandably, prefer to deliver on their promise. There simply is not the supply to meet demand, so it’s hard to see the double dose regimen lasting.
The politicians have created unrealistic expectations, however, in terms of delivering vaccines, when it has been is widely known that, for a variety of reasons, manufacturers simply cannot meet demand. Looking down the line, one wonders what will happen in 12 weeks if there are insufficient doses to give people the follow-up booster.