We have a patch at the end of our garden about 7.5x 4.5 feet. Because of previous building here, the earth is very sandy and unproductive and is London clay anyway.

It is very hard to get any vegetables to grow on it except tomatoes.

I have put a pic of it at

http://www.dthorpe.net/viewing

My wife suggests raising it and filling with decent topsoil. How high would be suitable and what depth of top soil would it need to be for both ease of working and decent growing. What kind of earth? Is raising it a good idea at all? I simply have no experience of this at all.

All advice gratefully received!