Mains adaptor needed for bubble tube fish lamp!

[ladypop]

We bought this
www.argos.co.uk/m/static/Product/partNumber/4321125.htm
Bubble fish lamp for DS1 3 years ago. I have tonight unearthed it for our DS2 and can't find the bloody mains plug/adaptor for it!
Odd question, but any ideas a to how I could get hold of one? Refuse to buy a new lamp at £40 a pop as this one would work perfectly fine! Grrr x