5" circumstance and 2 " tall -- Stamp marked pre 1898 -- by mark.   The stamping "C & S.W. Railway" paired with the serial number 19858 reveals that your bowl was custom-commissioned for the dining cars or station hotels of the Glasgow and South Western Railway (G&SWR), a major historical Scottish railway line.

C & S.W. Railway: This denotes ownership by the railway company. These heavy-duty hotel silver pieces were used to serve affluent travelers in grand dining cars or at the railway's flagship hotels, such as the famous St. Enoch Hotel in Glasgow or the Turnberry Hotel.

19858: This is a property inventory number. Because high-quality silver plate was frequently stolen or misplaced across an extensive transit network, every major serving dish was stamped with a unique asset tracking number to prevent theft and keep inventory.

The Manufacturer: The letters stand for Elkington & Company (originally founded in Birmingham, England).  The Crown Factor: If there is a small crown sitting directly on top of or inside the shield with the "E & Co", it indicates the piece was made before 1898. Elkington officially dropped the crown from their silver plate marks in 1898 to comply with new British hallmarking regulations. 

The Material: This mark was stamped exclusively on their heavy-duty electroplated nickel silver (EPNS) wares destined for commercial hospitality use, like the Glasgow and South Western Railway