Entrants may interpret the theme in any way, by writing, say, a letter which could change the world or a historical letter which could have changed the past. The three top prize winners in each category will receive Pounds 400 plus Pounds 600, Pounds 500 or Pounds 400 of electrical equipment for their school, and regional winners will receive Pounds 100 each and Pounds 100 for their school. Every entrant receives a "Letterbox" pack containing letters from famous people such as Nelson Mandela. Closing date: April 3. Details from main Post Offices or: RMYLW, FREEPOST 59, 62 Riverside, Rochester, Kent ME2 4BR, tel: 01634 296617.