Hello Silverfan
The mark "GBC with figure in the middle", as can be read in the book by Donaver and Dabbene, has been found only once on a teaspoon and the silversmith has not been identified.

On that teaspoon the shop mark is together with the guarantee marks of the Milan office in use until the regulation of 15 December 1872 came into force, just as together with the anvil mark is found here.
The tongs, in my opinion, are therefore manufactured before 15 December 1872.
The mark of "Italia Turrita", could have been affixed later, but I cannot explain why the silversmith's mark was also affixed again
Regards
Amena