Beat me to it! Never seen an international there though. When the World Cup was in Den Haag they used a football ground which is grass, they removed the grass and installed a (AFAIK temporary) artificial pitch. Can get away with the cost in Holland when you get close to 150,000 spectators in the week. Wonder if hockey in the UK ever got to the stage where a tournament can guarantee 20k/day spectators whether that's an option? Doubt they would use Wembley....but maybe a "smaller" ground? However unlikely, what makes it even less likely is the need for two pitches (one for warm-ups) in the nearness. Interesting that the Commonwealth games could be in Birmingham therefore not using Lee Valley; wonder where the hockey will be?