Cheers Worcester !
Right I have an update and a recommendation for all EDF users, although without working this out myself, I imagine this could work against you as well as for you in certain cases !
Finally been able to speak to the Green Team about this, been trying for days via phone & email
Their explanation why I have this figure is that its an average rate paid over "two periods" with two generation figs as the rate change 1st April and their systems assume using some complex calculation what you in theory will produce up and until 31st March
In my case I was paid 45.4p upto 31.3.13 and 46.81 after 1st April
These calculations and figs are NOT printed on the Invoice and only available to their computer systems on enquiry.
Goes away to review PVO mthly figs to see if this work in my favour or theirs this time !
Their recommendation by the way is each year take a reading 31st March and submit it via their online system, then it will be spot on !