solve

 sudoku

This is a puzzle rated as a 'fiendish' level of difficulty published in The Times on 1/4/05 - my thanks to The Times and Wayne Gould who set it. Red numbers are given to start off.

For a moderatly difficult Daily Telegraph puzzle and a graphical view of the logic used go here

The simple Su Doku rules:
Every row, column and 3x3 box must contain 1 to 9.
It therefore follows that the cell where a row and a column cross must contain a number unique to that row and that column (and box).

There may be several routes to the solution (see last step 6). This is the way I did it, warts and all.