An interesting Millennium dial has been opened in 2001 in Amble, Northumberland as part of a Town Square development. Click here if you would like to see it. Sundials usually don't show the same time as clocks.
Clocks generally run consistently at the same speed and indicate 'mean time'.
There are two main reasons why sundials show a different time to that shown on a clock or watch. Firstly because the earth neither travels in a circle round the sun nor travels in the same plane as our equator, shadows cast on a sundial move at different speeds at different times of the year. Few clocks can cope with this and for this reason a 'mean time' was devised to even out these variations over the course of a year. This correction is 4 minutes of time for each degree of longitude that the location of the dial is away from Greenwich. A dial is slow compared with a clock when it is West of Greenwich and fast when it is to the East.