Glad we've made contact & hope we can make sense of the Sinkinsons !
From my side from the IGI I have two likely candidates for my Robert Sinkinson, one chr.1772, the other 1776, both sons of Miles Sinkinson & Jennett ?. I presume the first Robert may have died young and the second one was named after him, often the case in large families.
The full list of the children of Miles & Jennett per the IGI is :
1. Elizabeth chr. 15/01/1771 Kendal 2. Robert chr. 16/01/1772 Kendal (see above) 3. Mary chr. 03/05/1773 Kendal 4. Miles chr. 27/12/1774 Kendal 5. Robert chr. 17/11/1776 Kendal (see above) 6. Elizabeth chr. 21/09/1778 Kendal 7. William chr. 03/11/1784 Kendal 8. Wilson chr. 27/11/1785 Kendal 9. Sarah chr. 14/09/1788 Kendal 10.Benjamin chr. 04/09/1791 Kendal
It looks also as if the above 4th son Miles married a local girl (Mary ?) and had a large family in Kendal of 8 children in Kendal, Underbarrow & Windermere between 1803 & 1823 per the IGI.
One further potential candidate for your George per the IGI is a George Sinkinson, chr Congleton, Cheshire 23/09/1753 son of Richard Sinkinson & Elizabeth ?. It's a long way from the Lake District. The IGI records are not always too complete so it may be a complete red herring.
Going back a generation, there is a Miles Sinkinson chr.1744 Kendal, with brother Robert chr.1735, both sons of another Miles Sinkinson & Mary ?. They would fit the dates.
I don't know whether this adds anything or just muddies the picture even more ! It doesn't really establish the link between your George and my Robert. Perhaps some further work on the IGI & with your UK researcher will be able to make some of these links.
If I come up with anything new meantimes I'll let you know. If you wish you can contact me off-list. Keep in touch & all the best