It took me a week or two, but I solved the problem of my foamy Theakston's BB clone.
So, the beer was/is really cloudy, but tastes OK. However, I was having serious issues with the about of head. In fact, the first 1/4 pint was non-heady because it had sat in the beer line, but subsequent beer was foaming in the beer line!!!!
I put this down to messing up either the amount of Cara pils or the Irish Moss.
Then it dawned on me........ I had dry hopped the beer as I put it into the keg. Upon the recommendation of a form member, I put the dry hops into a hop bag and tied it onto the bottom of the dip tube. However, I remember that when I installed the dip tube, it seemed that the bottom of the tube was resting over the hop bag. So, I wondered what the effect would be if you were to draw a carbonated beer through a mesh bag - surely it would cause foaming.
Anyway, I did a little surgery and removed the hop bag from the dip tube, and BINGO - I now have just the correct amount of head on my wonderfully cloudy best bitter