If you ever find a connection between your James & my ancestors, or any of the other Irvings in the area, I'd be grateful if you'd let me know. I've looked, but not found one.
My ancestor William Irving appeared in Bledlow in 1697, marrying a local girl. There were no Irvings in Bledlow before that, & only two references I've found to Irvings anywhere in Buckinghamshire, Oxfordshire or Berkshire. But in 1697, three Irving men married in the area: my William at Bledlow, a James Irvin at Fingest, & William Urwing at St. Georges Chapel, Windsor. Three years later, in 1700 David Irwing, married at St. Georges Chapel. Christopher appeared in Marlow in 1713, already married.
David was a very unusual name for the area, but common in Scotland, where the name Irving (& variants) is also common. All the Irvings seem to have been connected with the cloth trade, & all except my William settled in Marlow at some point. Bledlow was a weaving village, & my William's wife was from a family of weavers. It's well documented that large numbers of Scots chapmen had begun travelling around England at the time, selling haberdashery, & it seems likely that all our Irvings were Scottish.
Your James was recorded as 'of Reading' when he married in 1736, & aged 39 at his second marriage in 1751, putting his birth about 1712. I'm pretty sure he's not the son of my William, because as well as not finding a christening, there's no mention of James or his family in William's will, January 1737/8, a month after James & Elizabeth christened a daughter in Bledlow. He could have been a son of one of the other Irvings.