I would point out that Thatchers has been producing its Katy, Coxs and Thatchers Gold in 500ml for ten years.
Indeed, the 500ml bottle has been, and still is, the favoured option for other cider suppliers such as Westons, Aspalls, Sheppy's and Frome Valley.
Merrydown Vintage is packaged in one-litre bottles for the off-trade.
Thatchers has been selling Katy and Coxs and, more recently, Vintage in 750ml for some time.
Magners has led with a 'pint', or 568ml, bottle (with a one-litre option in the off-trade). As to who will own the category, only time will tell.