Welcome to the Forum.
I've seen that mark or similar attributed to George Hawksley & Co. in the past, and have not found any reason to doubt it.
Many platers made use of the 'crown' mark, and not only those of Sheffield, I've noted in past Birmingham and London outfits applying it to their products, so I would not use it as a possible link to tie in members of the Makin family, that best done by someone with a flair for genealogy.
There is still a mountain to be climbed regarding the research of many platers' marks, but new information does come to light and is helped along by people such as yourself who take the time to post mark images and share information.
It's good to hear that you find the website useful and hope you become an active member of the Forum.