Politicians did not pressure the UK Airports Commission to keep the option of building a new hub in the Thames Estuary on the table for future capacity expansion, says the body's chairman.
The decision to retain the option of locating a new airport at the Isle of Grain in Kent as one for further consideration in 2014 was "ours and ours alone", says Howard Davies.
"The shortlist of options was decided upon some time ago and has not been influenced by politicians. The Estuary option is one I will say, quite frankly, the commission went backwards and forwards on in our minds as to whether to keep this in play, and our conclusion, which is our conclusion alone, is that we do not have the evidence yet to make a firm decision, which is why we have chosen to do what we do."
Davies’ comments follow media reports that UK prime minister David Cameron met with him the days leading up to the publication of the commission's interim report and asked him to include an alternative to expanding Heathrow in its shortlist.
In its interim report, the commission has shortlisted two options to expand Heathrow with a new runway to the northwest of the facility or extension of the existing northern runway to 6,000m (19,700ft). A new south runway for London Gatwick is the third shortlisted option.
However, the report also leaves open one of the Thames Estuary options as a possible fourth alternative: a new airport to be built at the Isle of Grain.
Davies labels such a development "imaginative", but adds that construction would be a "massive challenge" and would cost in the region of £80 to £100 billion ($130-160 billion) to build.
He says such a scheme "cannot be regarded as a creditable option" at this time, but adds that a final conclusion to drop it could not reached until 2014 as "detailed work [to examine this option] has not been possible in the time available".