[Arran]

This set doesn't need a polarized plug at all, it's an AC set so the power transformer provides isolation. The power line caps are there to filter out power line noise, or some amount of it, they are ahead of the power switch but even if they were after the switch one is permanently connected between one side of the line and the chassis anyhow, which probably implies that you need to connect a ground to this receiver. On many sets the power transformer has an electrostatic shield built into it so no line capacitors are needed, on others there will be a single line capacitor connected across the line with no connection to the chassis. With a pair of .01 uf caps there won't be much current flow anyhow, unlike the B- to chassis coupling cap found in many AC/DC sets which are a .2 uf, where you can feel a bit of a tingle sometimes when you touch the chassis.
Regards
Arran