English taxpayers will be forced to hand over £5billion to the Scots to ‘compensate’ them for building the controversial HS2 rail line.

Despite the fact journey times from Glasgow and Edinburgh to London will be half an hour shorter, the Treasury has decided the project should be subject to the Barnett Formula.

This dictates the extra funding Scotland, Wales and Northern Ireland get for projects that affect only England.

Journey times from Scotland will be half an hour shorter, but the Treasury has decided the English project means Scotland should be compensated under the Barnett Formula

Ministers had always insisted Scotland – which already gets £1,700 per head more than England spent on it – would not be in line for any further handouts.

But figures slipped out in the Autumn Statement show that, in fact, Scotland and Northern Ireland will share an estimated £7.4billion between them. Campaigners against HS2 claim this will send the overall bill spiralling to £63.1billion.

The anti-HS2 campaign group, 51m, said the decision was ‘incomprehensible’.

Jonathan Isaby, of the TaxPayers’ Alliance, said: ‘Hard-pressed families in England will be livid to discover they have to fork out billions to Scotland, to compensate them for a project that many of them don’t even want anyway.’

A decision on whether to physically extend the HS2 high-speed rail link to Scotland has yet to be made. But the first 140-mile London-to-Birmingham stretch will see journey times between Glasgow and London reduced by about 30 minutes to four hours.

Anti-HS2 campaigners claim this will raise the overall cost of the project to £61.3billion

A second phase could then see two lines built in a V-shaped section to Manchester and Leeds by 2033, with travel times from Scotland to London cut even further.

The handout will further fuel the controversy over the Barnett Formula which – during the panic at Westminster over the prospect of Scotland voting for independence in last year’s referendum – ministers vowed not to change.