Cambridge airport

I'm a Masters student living in the Cherry Hinton area this year and I've noticed a lot of planes coming up and down the Cambridge Marshall airspace. Some of them look like small commercial planes you would see in domestic flights in Europe and in the UK but there are no regular flights advertised. Does any one know what goes on with all those planes? Are they mostly military? Corporate? Sport? Or a bit of everything?

Is this the one:
http://www.marshallairportcambridge.co.uk/

It says it's private so I assume it can be booked for any sort of flight but don't think easyjet/ryanair or any of the other usual companies use it...

If you're seeing large planes, it's also possible you're seeing traffic for RAF Mildenhall (KC-135s) and RAF Lakenheath, two of the largest airbases in the UK, both hosting USAF aircraft. You might also be seeing traffic for Stansted, which isn't far away. Duxford's also nearby, and is cause for the occasional DC-3 or Hurricane.