I carry 2 spare plugs, spare fuses, tape, wire, nuts & bolts. A set of Whitworth spanners, plug spanner, stubby screwdriver with interchangeable bits, allen keys, adjustable spanner, cable ties, pliers, rag and lead additive in my tool box ('59 A7 SS). All fits, just.
Had to be recovered once when the clutch loosened on its taper and sheared the key. Lapped in on during the repair and been OK since.
Z