The current way round is folk who sign Norwich don't sign Skegness. However there's a spare link who sign everywhere within reason so some sign the lot.
Back in the dying days of BR, from memory, the link structure (Drivers) was
Core : Lincoln, Grantham, Derby, Coventry (via Leicester/Nuneaton)
A : London-Sheffield (via Derby/Toton/Erewash), Derby-Crewe
B : Manchester (via Stockport, Romiley & Guide Bridge), Peterborough (via Grantham & Oakham), Derby-Birmingham
C : Skegness, Cleethorpes and freight work (Landor St, Kingsbury, Immingham, Brownhills, Bedford for Langley tanks).
There was also an ECS Lincoln-Nottingham via Newark & Grantham but can't remember where that fell.
Majority signed diversions via Corby, Stenson, Nuneaton-Whitacre Jn & Beighton as appropriate to link work.