Woburn Safari Park celebrates it's 40th birthday in 2010 and they are running a great promotion where you can get free entrance if you also turn 40 this year. Not a bad offer if you are born in 1970!
They are also running another offer where you can buy tickets for £1 for a max of 6 people to go on the actual 40th birthday of Thursday 20th May. There is limited availability on this one and tickets go on sale online on 8th April.
Full details for both offers-http://www.woburn.co.uk/news/article/celebrating-40-years/