Thanks for all the good feedback. Having read the posts I think I know what my problem is. Until now, my method has been:
1. Hit 50 balls...hmm, Not great. I must not be doing something the pros do in their swing. Solution - watch some videos and replicate.
2. Hit another 50 balls... Excellent. Something went well, figure out what I changed and exaggerate it.
3. Play 9 holes with my new pro swing. Think plane, think do not roll wrists, think left shoulder down, think hit in front of ball. oh damn,can't hit the ball to save my life
I'm starting to believe that great ball strikers are able to hit so well because they've grooved a swing and learned a feel over years and years, rather that following their own secret method of swinging that produces great results.
In fact, I'd say that sometimes maybe they don't even know how they do it! Just natural feel and instinct from lots of practice.
Maybe there really are no shortcuts in the painstaking game of golf :-)