LONDON, March 10 : British trainers Dan Skelton and Nicky Henderson will take on the might of the Irish at jump racing's showcase event with the likes of The New Lion and Lulamba vying for a share of the five-million-pound ($6.70 million) prize pot as the Cheltenham Festival opens on Tuesday.  Attracting some 200,000 racegoers across four days, the festival is worth an estimated 274 million pounds to the local economy boosting local restaurants, hotels and pubs.  It is also horse racing's