Nick,
thank you for taking and putting up the picture. You are further on than me, but it is not a race, so it does not matter that you are winning, - curse you!
Were the blast plates part of the kit? Even after the hours I have spent looking at drawings and photographs I have just found out about the anti blast shields that were fixed around the base of skylights and other deck features. The were meant to stop the wooden deck lifting as the blast wave caused a shock and vacuum. I will not be adding them.
James,
on page 59 of Brian King's 'Advanced Ship Modelling' is the picture you probably refer too. The previous page has one as well, but the plates are just partially shown. He shows them as a domino shape. He has joggled his deck planks around the barbette but not the blast plates, so presumably his interpretation is the plates are on top of the wooden deck, or he got fed up of joggling! If they were done like that, then hole would have had to be cut in the plates to allow deck fittings to stick through. As a model and full size ship they would be easier to make like small and rectangular.
So we have examples of them being done like that and as radial plates. It is possible that both methods were used on the different ships in the class so unless anyone comes up with a photo showing what Victorious was like I can choose to do it either way.