For the record, as I am really bad at remembering these things, I put my first batch of eggs on to hatch this morning.
I included a few Ixworth eggs (cream), lots of maran eggs (dark brown) and some blue ones. Some of the maran eggs have (hopefully) been fertilised by a blue-egg cockerel so any resulting female offspring will lay olive-coloured eggs. Obviously it would have helped if I had marked these, but to be honest I would only mix up the chicks when they hatch anyway. I am so rubbish at record-keeping.
N.B. Not sure how these will turn out especially as my number 1 cockerels and breeding hens all got killed by the fox.