This was due to "A BakEr' suggesting it :)

Thanks A BakER!  I tried your suggestion of lowering the pre ferment to 10% and this was the result.  It did not really do much in the fridge overnight so I let it stand at room temperature this morning for 4 1/2 hours ......... that did the trick!  Then after knock back and shape for an hour into the preheated Dutch Oven.

You were right the hydration was a little wetter than usual however it rose a treat :)  I adjusted the quantities and used 300g strong bread flour.

We went out for a picnic today so I had to take the cooling loaf with me!

This was the result, and it tastes quite yummy :)