ianw wrote:
The wife keeps banging on about converting a box room at adjacent to
our bedroom into an en-suite shower/wc.
Unfortunately the box room is at the front of the house and the
bathroom is at the rear (and on a slightly different level)
What would be the best approach?
put in a new soil stack at the front or use a macerator wc?

Yes.

Or take advantage of the slope and run it down along the joists out to
the back. Make sure you keep the switch for the macerator and the one
for the shower in different locations.