The original height of the 2900 Saints was , but the maximum height allowed for steam locomotives to work on the mainline by Network Rail is , because of overhead line clearances. The height of 2999 was therefore reduced, to allow it to operate on the mainline. Mainline operation also requires the additional equipment that none of the original members of its class had, including: AWS (A similar system called ATC was used by the GWR), TPWS, OTMR & GSM-R. However a later decision from Didcot regarding the ceasing of mainline running means that the engine will only see use at Didcot and on other heritage railways in the foreseeable future. Many names were submitted in a competition run by the group which were constructing 2999 and the name eventually chosen was "Lady of Legend". Other names that were submitted in the competition to name the new engine included: "Lady in Waiting", "Lady Diana", "Lady of Lourdes", "Saint Dai", "Maindy Court" (reference to donor loco 4942 Maindy Hall), "Prince Charles", "John Betjeman" & "Phoenix". An integral part of the Saint project is the 'Atlantic option'. Although it is intended by the Saint project that the completed engine will run primarily in its 4-6-0 configuration as a Saint because of the plan to go mainline, it is planned to have the engine run for a period during its 10-year boiler certification as a 4-4-2 Atlantic. The number it is expected to carry when converted into its 4-4-2 Atlantic form is 191 and the names include "Atlantic" and "Churchward". This mirrors the original Saint class of which 13 were built as 4-4-2s for comparative purposes and later converted to 4-6-0s.