HOME Secretary Theresa May made the right call when she tasked a judge to investigate the activities of undercover policing - but she made the wrong call by not extending the judicial inquiry's remit to Scotland.

Undercover policing is not in itself a bad thing – it is a useful tactic in disrupting terrorist groups and criminal gangs – but the way the practice has operated across the UK, including in Scotland, has been disgraceful.

Two Units – the SDS and NPOIU – have been found to have planted officers into peaceful protest groups that were merely exercising their democratic rights. In one obscene example, the SDS appears to have spied on the grieving family of murdered teenager Stephen Lawrence.

The treatment of women has been particularly abhorrent: undercover officers deliberately started sexual relationship with female targets and cynically disappeared when the women were no longer useful.

Along with Hillsborough, the undercover policing scandal casts an ugly shadow on policing across the UK that the Pitchford Inquiry may help lift.

However, May has set a geographical limit on the judge’s investigation. Undercover operations relating to England and Wales are covered, but not activity in Scotland. The Inquiry stops at the border.

This restriction is unjust for the simple reason that the NPOIU operated north of the border with the help of Scottish legacy forces.

Mark Kennedy, the NPOIU’s most well-known police mole, paid 14 visits to Scotland on undercover duty, including the key role of “transport coordinator” for the anti-G8 protestors at the Gleneagles summit in 2005.

Scottish officers like Paul Hogan at the old Tayside force were also seconded from their day jobs to work for the shadowy Met-based Unit.

However, the restrictive remit given to Lord Justice Pitchford means none of these activities can be scrutinised.

As we reveal today, even the Scottish Tories have now joined the cross-party consensus at Holyrood and Westminster in calling for the Pitchford remit to be extended to Scotland.

The case for such an outcome is overwhelming: the Inquiry should go wherever the evidence takes it, whether that is over the border or across the Irish Sea.

May was correct to set up the Inquiry in the first place. She must now ensure that the individuals spied on in Scotland also received justice.