With the need to drive the mini back to university the next day work began in the afternoon and went on until the small hours of the morning. At around mid night the engine was looking like this:
At 2am the engine was back together with help from Angus who found a new skill in cleaning cylinder heads with a cement trowel (for lack of a better tool).
The next day I drove the car to Brighton without a problem. It needs a good tune now after the gasket has settled and that will happen within the next week.