Martin, I've got quite a lot on 'my' Gillatts (even though I'm no relation), and checking backwards from your George Henry Gillatt, born Q1, 1884, reg district Gainsborough, it looks like George's grandfather, Henry, is the brother of 'my' John Gillatt of Winteringham. They all seem to originate from East Butterwick, Lincs (reg district Glanford Brigg).
In 1871, George's uncle, (another) Henry, is staying with John and Mary Gillatt and family in Winteringham, working as an apprentice to John, who's a carpenter/joiner.
Hope this makes sense! Not sure what you already have on George Henry, but I've got census pages, etc which I can send to you offboard from this branch of the family (ie the one I've adopted!!).
best wishes
Clare