The reason I asked (and was mainly geared toward those that attend both Regional and National events in the EoE - Carl Dufton, Simon Watson, Jonathan Brown) was because of the clash with a National/Regional date planned. However a specific National-Date-Clash-Rule (6.5) answered that one for me anyway.
The Manningtree Car show is moving this year from the 1st week of April to 19th June.
However, I have just read about a 1/8th and 1/10th National clash that could, if implemented, be solved by moving the 1/10th June 19th, fixture to the following week. If this (and I have no idea how likely) were to happen - problem solved!