You have to register on the website to attend, so that they have an idea of numbers :
"Because the events are free-of-charge i.e. we don’t sell tickets (and we’d like to keep it that way) it’s very important for us to get an idea of numbers. So by completing this form, your responses will help us a great deal in planning the smooth running of the day, making any improvements to future events and most importantly…knowing how you like your eggs cooked!"
http://www.goodwood.co.uk/site/content/ ... fault.aspx