When the £5 note was first launched last September it was hailed as being impossible to forge.

But now the polymer note is at the centre of a copycat scare and many people are questioning if they have a genuine note.

It comes as the Bank of England launches an investigation after police warnings about fake fivers circulating across the country.

The central bank has admitted there have been cases of the design being passed off on paper.

On Friday it said it was it was unaware of any forgeries of the polymer note, although its design had been crudely copied onto paper in a very small number of cases.

The scare started when a Dorset PCSO warned of counterfeit 'new £5 notes' circulating in her area.

If you are worried that your fiver is a fake here's six ways you can check to see if it is real:

  • Check the see-through window and the portrait of the Queen.
  • Check the Elizabeth Tower (Big Ben) is gold on the front of the note and silver on the back.
  • Check the foil patch below the see-through window changes from 'Five' to 'Pounds' when the note is tilted.
  • Check the coronation crown appears 3D (wiggle the note to see the effect).
  • Check the ultra-violet feature (a '5' will appear at the bottom left when UV light is shone on it).
  • Check the circular green foil patch on the back of the note which contains the word BLENHEIM - after Blenheim Palace, the birthplace of Sir Winston Churchill who appears on the note.

Alternatively if you're still unsure whether a note is fake, the Bank of England has a free app you can use on Android and iOS devices.

The central bank made the decision to switch from paper notes to polymer ones because the thin flexible material is believed to last 2.5 times longer than paper notes.

This is because the material is stronger so the notes can better withstand being repeatedly folded into wallets or scrunched up into pockets.

The old paper £5 notes will cease to be legal tender on Friday, May 5. If you have these notes you can exchange them at your bank or building society at any time before this date.