So which Birmingham - Wolves - Stafford path is this taking?
Will interestingly become the first regular (all day) Wilmslow-Birmingham service, might be well-used and relieve some of the XC services at Stockport/Macc.
The testing above related to Rail Adventure taking a class 350 from Crewe to Manchester Airport presumably just testing that this was physically possible with signalling, communication systems, clearance, timing etc. There was no need to test a 350 between Birmingham and Crewe as that was already a proved working.
There are four possible combinations of routes between Birmingham and Wolverhampton but I suspect that the Stour Valley route would be too congested. Years ago, before the road underpass at Tipton was built to avoid the level crossing, I used to visit the Tipton area and I used to see the barriers down for three trains, often five trains and on a couple of occasions seven trains. It was estimated that the barriers could be down for 42 minutes in the hour.
My guess is that Birmingham to Manchester airport would take a similar route to the Birmingham to Rugeley trains ie taking the Stour Valley route as far as Soho and then switching to the Grand Junction Route.