Interesting. I think you will find that the majority of these non AM / TH / GR folk who reached the 2nd round received WCS whilst going into Wimbledon outside the world top 250, some well outside ( Chris Eaton qualified )
They were of course part of larger groups of Brits, also no doubt containing further non top 250 WCs.
Given the numbers, some managed to get through one round.
I wonder how many would have got through this year if half a dozen Brits had been given main draw WCs.
Well, as they say, you've gotta be in it to win it.