"Andy Wade" wrote
| Briefly, there are two main earthing options:
| 1. Exported house earth
| -----------------------
| Simply 'export' the house earth via the armour of the SWA cable (the
| 'submain'). This will be fine for a dry timber shed with its floor
| raised well off the ground, so that it remains dry. ...

| Do NOT use this option if the house earthing is TN-C-S (PME) and
^^^

Should that 'and' be an 'or' (PME earths should never be exported)?

| For a tidy looking job use metalclad wiring accessories mounted
| side-by-side and coupled together using 20mm conduit bushes and
| lock-rings.

And I'd suggest running a green/yellow earth wire from the SWA gland through
each box and connecting to the earth terminal in each box and on each
faceplate, rather than relying on conduit-box-faceplate touching contacts.
Maybe you assumed this would be done, but better to be explicit.

Owain