These instructions are for setting up a sundial for GMT and are applicable for all sundials in the UK.
If you require a more specialised set up (ie local time), please add 4 minutes to the above value for every degree west of Greenwich and subtract 4 minutes for every degree east of Greenwich.
Most mobile phone solar noon apps will give local solar noon time. You can adjust the location of the app to latitude: 51.5degrees north, longitude 0degrees to show GMT.
To set up your spot on sundial make sure the top of your plinth is level, (use a spirit level), then fix your base in the centre of the plinth with rawl plugs and screws.
Next, secure the gnomon to the sundial plate using the 'U' shaped clip.
Insert the central fixing bolt into the sundial plate and turn with the spanner provided until it seats. Don't fully tighten at this stage.
At solar noon (see top of page), rotate the dial face until the shadow, and line of light, falls at mid day then tighten the central bolt using the spanner provided. Your spot on sundial is now ready for use.