Eventually I got it burning and it went REALLY well. I lit it around 12noon and took the pots out around midnight. I managed to get some great colour. In particular, a wonderful green which I think came from the brass bell filings. It was a worthwhile exercise and one I will do again, expecially in Spring when it's raining and cool - saves having an open fire that requires supervision outside.
Have a look at the results below. The last pot has been fired 3 times. I'm now happy with the outcome.