For more information on the series, please visit cache #01.
You are standing at the edge of what is now a new housing development, but what used to be the Cowbridge House estate. Due to its location, it was used for radar development during WWII. After that, technology companies continued to occupy the site.
When you leave GZ, you will pass a building on your left, The Old Mill, which used to used to be the social club of a Telecomms Company, the last occupier of the site before it moved to Swindon. To this day their social and fund raising efforts still go under the name of 'The Old Mill Social Club'.
For cache #17, you are looking for a small container.