Most Morgans seem to respond well to an "Italian tune-up" just before the emissions test.
My +8 is always marginal on emissions, but the local tester knows this and gets the cats really hot before testing , it gives him the opportunity to drive the car which he enjoys anyway.
Sorry I can't be more specific about the Lamda value and that lovely Series 1 ST220 engine , but there are many others here who know it well and will be along soon.
