As I trowelled off the surface of layer 6 I realised that I was seeing the natural sub-soil, a light brown mixture of pieces of chalk and clay. Bad news!
For anyone who hasn't read the earlier posts I was hoping to find the continuation of a ditch feature running into the garden from the boundary. The diagram below (not to scale) shows the location of previous digs, the possible direction of the ditch feature and the test pit I have been working on in 2007.
So, I have to conclude, at least, that the ditch doesn't run in a straight line. Tantalisingly the natural surface slopes off towards the edge of the test pit (on the boundary side). Does the ditch continue but not in a straight line? Or, perhaps it isn't a ditch at all. It could be a hole dug for some practical purpose like the acquisition of clay.
Watching Time Team prepares you for such set backs! I will have to regroup, consult the "Mick Aston" within and decide how to proceed.
In the meantime, the grass needs cutting!