Strange mysteries of Sir George Duckett

This lovely little lock cottage on the river Stort is up for sale.

Maybe because it lies opposite a brand new, about to open, marina.  Let's look closely at the sign over the door.

GD 1830 and a mysterious hand. That's GD for Sir George Duckett.  We presume that is the man after whom Duckett's cut, or the Hertford Union Canal, is named.  Here I get confused.  Sir George Duckett died in 1822 and Duckett's cut was er cut in 1830.  Is that anything to do with the 1830 over the door?   And what is the hand all about?

GD had been a leading light in the creation of the Stort Navigation and in Bishops Stortford there is a Duckett's Wharf.  Reading up on the man, is confusing.  For a start he seems to have been called George Jackson until he became a Baronet and changed his name to Duckett.  It gets a bit easier, or not, when you find he had a son George.  It seems it was George Junior who sponsored Duckett's cut.  He went on to try and get the Stort Navigation extended to Cambridge, but failed.

Hmm all the bits I have browsed on this are unclear about which Duckett they are talking about.  Anyway, on to the final spooky mystery about Duckett's cut.  Has anyone else noticed that it is a straight line pointing directly to the Gherkin building?

How did GD work that one out?  Is it on a lay line?  Is the Gherkin more than just an office block? We should be told.