Fun and suitable to do with children. It is part of the Church Micro Series... the largest series anywhere in the world! (by sadexploration, whom you should contact if you want to expand it → see bottom of description for more infos)
St Michael and All Angels is a (in my humble opinion) beautiful church at the heart of Bedford Park, Chiswick. It's a Grade II* listed Church of England parish church and was designed by the architect Norman Shaw, who built some of the houses in that area. The church was consecrated in 1880 and is constructed in what has been described both as Queen Anne revival style and as Perpendicular Gothic style modified with English domestic features. Its services are Anglo-Catholic, which refers to people, beliefs and practices within Anglicanism that emphasise the Catholic heritage and identity of the various Anglican churches. It features a nice garden and bench/memorial as well as those pretty red bricks of the late 1800s which are typical for the buildings designed and errected for the 19th-century bourgeoisie in Bedford Park and Chiswick as a whole. The same kind of bricks you will find on other churches in the area (check for the Church Micro Series traditional and multi-caches in Chiswick, there should be quite a few!). Take a look inside if it's open!
More infos at http://www.smaaa.org.uk/wp/
At the coordinates of the multi, you won't find any cache but the clues needed to complete the first stage of the multi.
Stage 1 - (at the given coordinates for the multi). At these coordinates, you should see a stone on the outside wall of the church, at about 1,20-meter height. This stone was laid by Mrs Wilson on the 14th of May, 188B.
For stage 2, 3 and 4, and to learn more about how to calculate the final coordinates: see description of the waypoints / stages.
You can check if you calculate it the final GZ right by visiting geocheck.org. 
Have fun!
**************************************
For full information on how you can expand the Church Micro series by sadexploration please read the Place your own Church Micro page before you contact him at churchmicro.co.uk
See also the Church Micro Statistics and Home pages for further information about the series.
*************************************