Bike rack for work car park - ideas?

Hi all,

I've been tasked with finding a bike rack for up to 20 bikes, to fit
inside a standard car parking space at work. An added complication is
that we share the car park with a number of other offices, and since
we've paid for the space don't want to the rack to fill up with
everyone else's bikes.

So, was wondering whether it's possible to buy a rack with an
integrated locking mechanism - so we could give our cyclists a key to
unlock their space? Remember seeing something like this at Cambridge
station ("premium bike parking spaces", for a fixed fee) - any idea
where I could find something similar?

Or perhaps we could adapt a standard rack? Apart from the lack of
locking mechanism, I like the look of these, for efficient use of
space: http://www.cyclepods.co.uk/

Any thoughts, ideas much appreciated.

Many thanks!

Russell