In message , at 12:36:08 on Sun, 8 Apr 2018,
tim... remarked:
The cost of the land is understood to be just under £300m to the
housebuilders, with the finished value of the sites nearing £1bn.

So that's about £350k per house; of which £100k is its share of the
land, another ~£100k for the construction of the house, plus £150k
for building the roads and drains, contributions towards schools and
other amenities, subsidies for "affordable" homes,

ITYF that the latter comes in at about 30K per house

Can you show your working, in terms of the discount that's being offered
by the builder and the percentage of affordable homes on site?

and a small profit for the developer.

leaving

And the "the roads and drains, contributions towards schools and other
amenities"?

a big profit for the developer

What's the industry standard margin for this kind of development? A
quick google suggests that 20% would be regarded as "record breaking"
(although that's what I'd expect on a much smaller development).

15% of £350k is close to £50k, which neatly gives £100k again for the
non-residential infrastructure, community contribution, and loss made on
the affordable houses (which I'd expect to be changing hands at about
£250k).
--
Roland Perry