WHEN ( be positive ) you have all the unclued lights which are entered as 1st 2nd 3rd 4th etc you complete the grid, fill in your name and address and post it off. ( Oh! And hope you win! )
The Spectator, EV in the Sunday Telegraph, Mephisto in the Sunday Times etc, are more challenging than normal cryptics but the key is perseverance. It's a case of practice makes perfect ( or nearly perfect. )
Best wishes and happy solving.