Adrian Pepper is Managing Director of Pepper Media and the founder of consumer group Open Sundays.

The Scottish Nationalists’ decision to oppose reforms to the Sunday trading laws in England and Wales has laid bare their cynical brand of politics.  Just as they did to the modest proposal to bring hunting laws into line with those in Scotland, they now want to deny the people of England and Wales the same freedom to shop as enjoyed by the people of Scotland.

The reason given for their stance – that this reform would impact on the pay rates of shop workers north of the border – is a mere fig leaf. They care only about the bigger game of breaking up the United Kingdom.  It suits them very well for Scotland to have different laws to the rest of the UK.  The more they can make our countries different, the stronger the case for partition.

By interfering in English and Welsh affairs, the Scots Nationalists hope to provoke a furious reaction and ultimately engineer a constitutional crisis. But David Cameron, George Osborne and Sajid Javid are too canny for that: they will react with cool heads and English reserve.

In time, English votes for English laws (with similar protection for Wales) will be bedded into parliamentary procedures, and these Sunday trading reforms will pass. For without them, shopping will become a more tawdry experience for the ever-increasing number of Sunday shoppers who have to sit on their Ipads before driving to the shop collection point to pick up their goods.

Like any leisure activity, Sunday shopping in retail outlets presents an opportunity to congregate, to interact and bond with others, to discuss what we like and don’t like, to learn more about the world around us and to reach agreement with family and friends on what big ticket items will benefit us the most. It is already the most popular day of the week for families to go on an outing to the shops together – and the longer the stores stay open, the more chance they will find other things to do as a shared family experience, like eating together, going to the cinema or attending other community events.

Some traditionalists think that the Scots Nationalists’ intervention will preserve Sunday in England and Wales as a quiet day of reflection. They are already free to spend Sundays as they wish – but most of us want to make Sunday special for us through exercising our own choices.  In Scotland, where shops can open when they like, Sundays are still just as special as in England. America is one of the most religious countries on earth, and yet the shops are open 24/7 in most States.  Sundays can be special there, too.

The Government’s reforms to Sunday trading would devolve the power to liberalise opening hours to local authorities in England and Wales.  Yet the Scottish Nationalists are opposing this devolution measure.  Nationalist parties are entitled to use political means to achieve their objectives, but they need to be careful not to lose their principles along the way. It is a strange form of nationalist party which no longer stands for the right of a nation or community to govern itself.

Like Liberal Democrats in disguise, the Scottish Nationalists are ruthless in pursuing their political objectives. But unlike the Liberal Democrats, they are good at it.  Siding with the unions in Scotland on Sunday trading is a direct political challenge to Labour.  Little do they care that by ganging up on the many Sunday shop workers who choose not to be members of a union, they are preventing people who might only have the chance to work at weekends – and people who have caring responsibilities at home –  from earning extra pocket money and a little dignity and independence for themselves.

The Scottish Nationalists’ pact with USDAW represents a shift to occupy new ideological territory.  Their politics is now a lethal Molotov cocktail of both nationalism and socialism, which bears close resemblance to the statist politics of early twentieth century Europe.  Fortunately, most of us want to live in a more modern, dynamic, outward looking and free society than them.