The Aga dual-fuel range grill regulator is connected as follows and the Rangemaster is probably the same.
Live in from main terminal block via a cut-out to P1
Neutral from main terminal block to 4
Inner grill connected between 2 and 4
Outer grill connected between 2 and P2
S1 and S2 if used are for the neon indicator.
Hope this helps. If I can find an actual conversion chart I’ll put another post on.