When is a sterling fiver not worth the paper it is printed on?

The answer is, when it is not printed on paper in the first place but on polymer – the thin, flexible plastic material that is set to replace the traditional paper £5 note in the UK.

The Bank of England officially launched its first polymer note – a £5 featuring Sir Winston Churchill – on Tuesday.

The bank has printed 440 million new fivers on polymer which lasts 2.5 times longer than paper and is resistant to dirt and moisture.

It also plans to introduce a new polymer £10 note that will feature Jane Austen next summer and follow this up with a JMW Turner £20 note by 2020.

The new fiver may be a first for the Bank of England but it is 17 years behind the first trend setter to embrace polymer bank notes – Northern Ireland's former Northern Bank, which is now part of the Danske Group.

Polymer

Back in 1999 Northern Bank issued its own £5 polymer special edition note to celebrate the millennium.

At the time the bank was owned by National Australia Group which also issued polymer notes in other regions.

Northern Bank issued two different polymer notes – a standard plastic £5 and a “Year Y2K” note – which was a collector’s item in a presentation wallet.

About two million notes went into circulation and although the notes are still “exchangeable and usable” today the bank stopped issuing them in 2008 and has not printed any new stocks since then.

According to Danske it is not possible to calculate how many are still in circulation – or lying forgotten in the back of a drawer somewhere.

But judging from the revived interest in Northern Bank’s polymer £5 note on various online retail sites yesterday it might be worth trying to locate one.

What was described as an “extremely rare £5 Polymer Northern Bank bank note” was on sale online yesterday priced at £125.