Hello and Welcome,My name is Frank, I am a Personal Property Appraiser and would be happy to assist you with your question.
Based on the marking as well as the well as the Registration or RD number, your jugs would have been produced by the Simon Fieldings Company Ltd in Stoke On Trent, Staffordshire, England in 1903. These would have been produced at the Railway Works, prior to the renaming of the Crown Devon Works in 1910.
In the current market early 1900 S F & Co Crown Devon Jugs can bring between 20 -40 GBP based on size, decoration and condition. Many of these were matching sets that would come in various sizes, the smaller of which would bring a bit less than the larger. Matching sizes would bring roughly the same value, but would rely more heavily on the overall condition as a sales point.
Any damage to the jugs such as cracking, chipping or any crazing would detract from the resale value.
I hope this information was helpful to you today,Best of luck with your vintage china,Any feedback you can leave for my service would be much appreciated,Thank You,FrankPlease let me know if you have any further questions or photos as I would be happy to assist in anyway that I can.