The only problem with this method is that the resulting value will be in text format so that if you want to add a column of numbers with the £ sign (or Euro € or Yen ¥ or any other monetary or numerical symbol) you won't be able to.
The way around that is to define a Custom Format. As in the article, insert the desired symbol into a cell and copy it to the clipboard
In the "Type" input area paste your symbol and "0.00" if you want decimals or just "0" if you don't.
You can format a series of columns or rows this way or use the format painter to apply the custom format to individual cells.
The drawback is that this custom format will be valid only for the current workbook. You would have to redefine it in any other workbook. You could make the custom format universal via templates or macros but I've never found the need to since I use these symbols rarely and it is so easy to define when I do need them.