Help!

In brief...MGB would not start. Finally towed it to a garage. New coil, plugs, points, condenser. Mechanic took it for short drive. Ran fine. Would not start again. Towed her home. Cleaned carbs. Started and ran fine. shut off. WILL NOT START. Plenty of gas, spark, etc. No manifold leaks. Fuel pump ok. Will not start with choke out, or in. Twin su HIF4s. This is weird. Hope someone can come up with a scenerio. Thanks. Next step is to rebuild carbs, although I think it's a waste of time.

Clean and check the Air throttle plate.
Exercise by hand!

If you have relay(s) for the ignition, it might be useful to check the connections or change the relay itself. I had a similar problem. It was difficult to track down, because the fault was intermittent. Good luck!