Bognor and Selsey do get some tornado activity, these are normally formed in the transition between high wind speeds blowing in from the southwest and the slower slack winds in the lea of Isle of Wight and are classic spin off tornadoes.
Here is a diagram that I posted back on the 30 July 2005 to help explain why they are so common here, after one of the Selsey Tornadoes or it may have been one of the Pagham harbour Tornadoes.