These are a fairly standard style pair of bright cut tongs, probably dated from around 1780 - 1784. The "SW" maker's mark is usually attributed to Samuel Wintle but we cannot be sure of this.  What is fascinating about these tongs is that the maker's mark is struck on the inside, just underneath the bow and the hallmark is struck on the outside at the top of one arm. We know that sometimes tongs are hallmarked on the outside, but I have not seen any where the maker's mark is on the inside and the hallmark on the outside.

Click here to see Benjamin Mountigue tongs hallmarked on the outside
Click here to see Thomas Tookey tongs hallmarked on the outside.