Chris Hogg wrote:

I heard minigod Nige say that the dues we'd receive on EU imports to
the UK would be greater than the dues we'd pay on our exports to the
EU. Whether the Delors analysis takes that into account, I didn't go
looking.

It does mention that if we end up with WTO trade, the dues the EU would
receive from UK trade could halve their "brexit gap" but would
eventually see individual EU states income drop - whether they'll allow
that to influence their decision to allow us better than WTO trade,
we'll have to see.