The IL over IR (without pellets) maker's mark of John Langlands I & John Robertson I is an overstrike on another maker's mark. What we do not see is the Newcastle "3 castles" in a shield, guild mark, or the expected provincial style lion and there is a lower case "t" that was not used at Newcastle until 1882.The original maker was a "PB" and considering the lion and "t" and probably from London. The PB maker, I guess was Peter Bateman, but with Anne Bateman, the widow of Peter's brother Jonathan, and the full mark would have been PB over AB. The lower case "t" should be for London 1794 and Peter and Ann worked together in the 1790's.
Further information taken from the web site silvermakersmarks.co.uk suggests the no pellet Langlands Robertson mark has only been seen on Newcastle hallmarked silver dating to 1782, but on silver with London guild marks with dates from 1782-1794. Also stated is that the London hallmarked Langlands and Robertson silver is "often overstruck on a London maker's mark". The Langlands Robertson partnership ended in 1795, but John Langlands was suggested as dying in 1793. Could Langlands' death been a factor towards the "buying in" of the set of sugar tongs.
Fishless