This is a fairly straightforward urban micro. Finding it should not take much effort, retrieving it and replacing it unseen should provide a bit more of a challenge.
For obvious reasons, please be as discreet as possible when approaching this cache and hide it as well as you can. You may notice that the cache site is overlooked by a CCTV camera. I have contacted Hertfordshire Police to explain what they may observe going on, and that it's an innocent game (and I gave them the geocaching website URL too). They seem quite happy with this, so you should not need to worry.
There is a gift in it for the cacher who is the first to find, otherwise miniscule swaps only!
While you are in the area, why don't you try out two other local caches : Berkhamsted Historic Georamble, which passes close by this cache, or Sinus Ring?