lowest numbers and locomotives were renumbered in order of age. When the London, Tilbury and Southend Railway (LTSR) was absorbed by the MR in 1912, its locomotives were renumbered into this scheme. It had only two tender engines, both 0-6-0 types, and these became 2898 and 2899. The rest were tank locomotives of varying wheel arrangements, which required the adoption of new number ranges at the end of the tank engine series. In all, the number ranges used by the MR were as follows: Note: While the majority of ex-MR locomotives were left unrenumbered by the LMS at Grouping in 1923, the ex-LTSR locomotives were subject to several renumberings to clear space for new stock, which changed the number ranges set out above. Post-Grouping Numbering Shortly after the LMS was formed in 1923, it developed a new numbering scheme for all the locomotives that it had inherited. The scheme dealt with two key problems faced by the new company: There were many locomotives with the same number, as each of the constituent companies had used a series starting at number 1 Many of the constituent companies had numbered their locomotives in a somewhat random way, and the renumbering allowed for all locomotives in the same class to be given consecutive numbers and similar classes to be numbered in blocks These advantages more than overcame the disadvantage of the effort involved in renumbering almost every locomotive and giving them a number that usually bore no relation to its pre-Grouping identity, except for the Midland Railway locomotives that had been renumbered along similar lines in 1907 and mostly retained their numbers. The system comprised four groups of numbers into which locomotives from a set of railways were numbered: Within each group, locomotives were numbered in blocks which ran (low to high numbers) as set out below. Within each block, the least powerful locomotives took the lowest numbers. When the Somerset and Dorset Joint Railway locomotives were absorbed in 1930, they were mostly allocated numbers in the Midland Railway series (appropriate, since the SDJR had been jointly owned by the Midland Railway and many MR designs had been used on the SDJR), though some took numbers in the former LNWR series. New Locomotives New-build LMS locomotives were not allocated any particular numbers, but were fitted into the most appropriate division. The unallocated 13xxx series of numbers were also used for new build LMS