If "signed contract" is your requirement then we can agree that no politician has ever lied in their campaign promises, because they don't make them signed contracts... that seems irrelevant?
The lie was that we save that much by leaving the EU, the fact that our health service was underfunded and has had budget increases in line with inflation and population growth doesn't change that it was a lie - we could've (and would have) increased NHS spending regardless of the Brexit vote.
The lie was that we save that much by leaving the EU, the fact that our health service was underfunded and has had budget increases in line with inflation and population growth doesn't change that it was a lie - we could've (and would have) increased NHS spending regardless of the Brexit vote.