Thanks for your reply. I had forgotten our previous correspondence.
In case it is of interest I offer you the following information. In the codicil to his will (1853), Arthur Stanley says. "I give the silver salver presented to my grandfather by the Merchants Corps of Dublin in 1798 to my nephew Captain Arthur Wyndham (my GGG Uncle). I have discovered that in 1798 a group of 21 bankers and merchants of Dublin, one of which was an Arthur Stanley, requested the Lord Mayor of Dublin, Thomas Andrews, to call a meeting "to take into consideration a measure of the utmost importance to this kingdom". Clearly htis was the Irish Rebellion of that year.
I therefore intend to follow up this lead in Ireland. Just to confuse matters, the IGI has a marriage of an Arthur Stanley to a Sarah Wyndham on 20 May 1816, though his surviving wife was Elizabeth Lowther Stanley. Perhaps it was his first marriage, though this would make him twice connected to the same branch.
Best wishes, AlexAsh