BBC News Online: UK

Change for a tenner

More than £4bn worth of the banknotes, which see naturalist and scientist Charles Darwin replacing author Charles Dickens on the reverse side, have been printed.

The Bank of England has released an undisclosed amount to banks, building societies and post offices throughout Britain.

As well as the traditional features of the watermark and metallic thread, it includes anti-copy devices.

But the note also carries an invisible figure 10 that only shows up under ultraviolet light.

The word "Ten" is written alongside the figure but in lettering so small it can only be read with a magnifying glass.

A brightly-coloured foil hologram of Britannia or the figure 10 also features.

The portrait of Darwin on the back includes objects related to his life and work.

The HMS Beagle, a Galapagos Islands hummingbird, flowers and Darwin's lever compressor lens are shown.

Legal tender

At the end of February there were about 568 million £10 notes, 209 million £5 notes, 659 million £20 notes and 84 million £50 notes in circulation.

Bank of England officials said the "Dickens £10" will remain legal tender for some time after it is no longer actively circulated.

But many will quickly disappear from circulation as notes are recycled every 18 months to two years.

The Bank's chief cashier, Merlyn Lowther, whose signature appears on the notes, said: "We have carried on to this new note the enhancements which were introduced with the new £20 last year, and which have been very successful.

"Anti-counterfeiting and cost effectiveness are the two key objectives of our banknote research work."