I believe the "seating" issue on the new SSL S-stock has been decided.
It will be the same for all cars - whether formed as 6, 7 or 8's. This
will mean a slight increase in seats on the Circle/H&C Lines (and even
more so if station rebuilds allow for 7-car operation), but a reduction
of 32% on the Met Main. Still, presumably they'll need all that extra
standing space for those displaced off of Chiltern? The good news is
they'll have air con (in the driver's cab only mind you...).