Speed Six. Failed MOT on emissions, (again).

[quint22cp]

Got new Lambda sensors (from Powers, the expensive ones.
New CATs (£400 each).
New exhaust.
Injectors cleaned and flow tested, all perfect.
New air filter.
Throttles balanced.
New plugs & leads, (old plugs looked a perfect colour when they came out).
Not faults on ECU, reset adaptives.
CO reading well in limit.
HC reading well in limit.
Lambda reading 1.079, limit is 1.03
Tried everything, revving it, fast idle, rag up muffler.
Could not get the Lambda to come down.
Always had this issue since I bought the car, don't reckon it has ever passed from new. Used to go to friendly MOT man but he's retired and now can't do that.
Does anyone know how to adjust the mixture to lean it out so the Lambda comes down ?
Well miffed