No need to apologise - it is a confusing debate, and is not helped by my typos!
I don't think it is a contradiction because both LHR and LGW understood that the airport's commission was to reccomend one new runway only (i.e. LHR or LGW - not both).
Therefore, it was right for each airport to put forward its business case on the basis that the other would not proceed for a significant (I think 20 year?) period.
Does that clarify the point?