The Mayor of London starts by saying that although he campaigned against Brexit, he accepts the results - despite London voting against it.
He says "of course" there are examples where no deal is better than a bad deal, but says that returning to WTO terms which would equal a "catastrophe" for London's service industry.
The service industry represents roughly 90% of London's economy.
He acknowledges that some of the worst-case scenario predictions have not occurred, but stresses that some service industry leaders, including UBS and HSBC, had said they would potentially move some of their business.
He says that an "interim deal" would offer security to service industries which would secure access to the single market whilst a final deal is struck.
The Mayor of London Sadiq Khan is the latest person to give evidence to the Exiting the European Union Committee.
This is part of the committee’s inquiry into the UK’s objectives for withdrawal from the EU.
London voted significantly in favour of remaining in the EU, contrasting with England as a whole.
Welcome to Westminster coverage for today, as we follow committees and debates in the Houses of Parliament.
First, we're turning to the Exiting the EU Committee, who are questioning London mayor Sadiq Khan.