"That's the argument of Lord Jim O'Neill, the former Conservative Treasury minister and Remain supporter" So not at all biased then.

Of course he is biased. Even now he is a Remainer.
When he was in the Treasury, it told us that voting Leave would have an "immediate and profound" effect on the economy, cause a huge rise in unemployment and necessitate an emergency budget to raise money.

How many voters were influenced by such dire predictions from the Treasury and august bodies like the IMF. More than by the disputed bus prediction I am sure.
I was certainly forced to think twice and reconsider.

Had they won they would never have admitted it was all bollocks, and probably deliberate lies.