Like getting tipsy in a pub? Sorry, but you are breaking the law!

ENJOY your roast potatoes this Sunday lunchtime... unless they’re Polish.

Spuds imported from the eastern European country are illegal – so tucking in could land you in very hot water indeed.

If you weren’t aware of the risks you’re probably not alone – as the legislation is one of a series of strange rules that many Britons won’t realise are still on the statute books.

Handling salmon in suspicious circumstances could also land you on the wrong side of the law, along with legislation that forbids drinkers being drunk...in a pub.

Cambridge University law academic Christopher Sargeant said our long legal history means there is inevitably a body of out-dated and obscure rules.

His list of the ten most unusual offences, released yesterday, includes a 14th century rule that anyone who finds a sturgeon or a whale on a beach must first offer it to the Queen.

Although odd, some laws have stayed in force because they served a purpose in more recent times. The Polish potato law dates from 2004 and was designed to keep ring rot out of the country. The salmon law – banning the handling of fish suspected of being caught illegally – was a 1986 measure to crack down on poachers.

The ban on drunkenness in pubs dates from Victorian times and was aimed at encouraging sobriety among the poorer classes.

The law may seem outdated when modern society routinely tolerates large- scale public drunkenness fuelled by binge- drinking. However, it has been used in recent times against drunks driving golf buggies – and in 2009 against a man who rode a horse bareback through Wallsend in Tyneside after drinking several cans of lager.

‘This reflects that even the oldest laws can still serve a key purpose, even if this is not always immediately obvious,’ said Mr Sargeant.

The laws on his list, compiled with Privilege Insurance, have survived repeated attempts by Whitehall to remove and repeal them. Some oddities have been successfully abolished, including a 1541 act that ordered every man to keep a longbow – which survived until 1960. Also kicked out was an 1898 law forbidding gambling in a library.

Popular beliefs that it is treason to stick a stamp with the Queen’s head the wrong way up have never been real laws, Mr Sargeant said. ‘Given its rich and varied legal history, it is inevitable that the UK has had its fair share of weird and wonderful laws,’ he added.