By giving the title of these pages as 'Ruislip Woods' I am somewhat generalising as technically the area comprises of Park Wood, Mad Bess Wood and Copse Wood with Ruislip Lido at their centre. However Ruislip Woods is how I know the place so it will do for me.
The woods are a National Nature Reserve and have been since the late 1990's and as such was the first place in London to achieve this status. Since the 1950's the woods have been designated a Site of Special Scientific Interest (SSSI.)
Prior to all of this designating, the woods have been around for thousands of years and are a remnant of forest that covered much of Middlesex (is Middlesex a County anymore, anyone?) The Lido was created as a resevoir in in the C19th to supply water for the good old Grand Union Canal.
Back in the day after being a prehistoric wilderness the woods were used for hunting and farming and cattle are still to be seen roaming about in the Poor's Field meadow land to this day! Interestingly the woods were once owned by the Knights Hospitallers, cousins of the Knights Templar, a bunch of warrior monks who did a large amount of Crusading in the C11th.