Under an agreement announced yesterday, the order has been capped at 34.8 million doses. The government will not pay a cancellation fee after both sides agreed that the settlement – the terms of which were not disclosed – represented "fair value".
Ministers had ordered enough vaccine to protect the entire population if needed, but they were later advised by experts that that contingency would no longer be necessary.
Health Secretary Andy Burnham said: "This deal means the UK will save approximately one-third of the original value of the orders with GSK. This both protects the public purse and ensures the UK remains at the forefront of pandemic preparedness worldwide."
GSK, which is the biggest supplier of H1N1 vaccine, has already reached agreements with Germany and Belgium to cut vaccine orders by those countries.
The UK health department negotiated with GSK on behalf of the devolved administrations.