This is only my guess.

I don't know it...." King must have taken the manuscript to Lord Oxford and Lewis, and been present at its reading.

When that reading actually took place is not ascertainable; but there is no doubt that before March 15th, 1738, King was aware of the criticisms made on it.
On that day he writes to Mr.Deane Swift, explaining that he has been obliged to defer the publication until he has received Swift's answers to the objections made by the friends who read it.

On April 25th, 1738, King wrote again to Mr.Deane Swift, regretting that he could not see him, "because I might have talked over with you all the affair of this History, about which I have been much condemned: and no wonder, since the Dean has continually expressed his dissatisfaction that I have so long delayed the publication of it.

However, I have been in no fault: on the contrary, I have consulted the Dean's honour, and the safety of his person.