Graham,
In parts of Somerset, MTO2 is the 'working grade'. In my area, MTO3s' duties include 'specialist areas'. Apart from that, there isn't any demarcation between the grades.
I would assume, but I don't know, that my manager would be equal to an MTO5.
Would I be far from wrong if I was to assume that line management should be within two grades above the highest grade technician, or am I living in 'cloud cookoo land'?
Cheers
Mark