[Nuvistor]

C1 is part of the isolation required due to this being an AC/DC chassis, must be a Y type capacitor, you will probably find the original is a wax paper type with 300VAC working. It also with C3 provide a capacitive potential divider with C1 to bottom end couple the external aerial to the aerial tuning coils.

R1 has been noted for static discharge, I am not sure what R2 is for unless the aerial tuned circuit requires a DC connection to chassis.

It is standard circuit that Ekco used in a number of their radios. The Trader series of circuits very often have a brief circuit description unlike the Ekco Manual, look at those for the above description.

A word of caution, this radio uses a live chassis technique, use an isolation transformer in the power line, this will give you some, not all, protection and allow you to connect test equipment for any measurements you take.