LMS Rebuilt Royal Scot Class

{{Short description|British steam locomotive class (1943–1966)}}

{{Use dmy dates|date=March 2017}}

{{Use British English|date=March 2017}}

{{Infobox locomotive

| name = LMS Royal Scot Class

| powertype = Steam

| image = Camden Locomotive Depot geograph-2741547-by-Ben-Brooksbank.jpg

| alt =

| caption = 6127 The Old Contemptibles, as rebuilt in 1944

| designer = Sir William Stanier

| builder =

| ordernumber =

| serialnumber =

| buildmodel =

| builddate =

| totalproduction =

| rebuilder = LMS Derby Works

| rebuilddate = 1943–1955

| numberrebuilt = 70

| whytetype = 4-6-0

| uicclass = 2′C h3

| gauge = {{track gauge|ussg|allk=on}}

| leadingdiameter = {{convert|3|ft|3+1/2|in|m|3|abbr=on}}

| driverdiameter = {{convert|6|ft|9|in|m|3|abbr=on}}

| minimumcurve =

| wheelbase =

| length = {{convert|63|ft|0+1/2|in|m|2|abbr=on}}

| width =

| height =

| axleload =

| weightondrivers =

| locoweight = {{convert|84.90|LT|t ST|abbr=on}}

| tenderweight = {{convert|54.65|LT|t ST|abbr=on}}

| locotenderweight =

| tendertype =

| fueltype =

| fuelcap =

| watercap = {{convert|4000|impgal|abbr=on}}

| tendercap = {{convert|9|LT|t ST|abbr=on}}

| sandcap =

| boiler = 2A

| boilerpressure = {{convert|250|psi|MPa|2|abbr=on}} superheated

| feedwaterheater =

| firearea =

| tubearea =

| fluearea =

| tubesandflues =

| fireboxarea =

| totalsurface =

| superheatertype =

| superheaterarea =

| cylindercount = Three

| cylindersize = {{convert|18|×|26|in|mm|0|abbr=on}}

| valvegear = Walschaerts

| valvetype = Piston valves

| valvetravel =

| valvelap =

| valvelead =

| transmission =

| maxspeed =

| poweroutput =

| tractiveeffort = {{convert|33150|lbf|kN|2|abbr=on}}

| factorofadhesion =

| trainheating =

| locobrakes =

| locobrakeforce =

| trainbrakes =

| safety =

| operator =

{{unbulleted list|London, Midland and Scottish Railway|→ British Railways}}

| operatorclass =

| powerclass = 6P; reclassified 7P in 1951

| numinclass =

| fleetnumbers = {{unbulleted list|LMS: 6100–6169|BR: 46100–46169}}

| officialname =

| nicknames =

| axleloadclass = BR: Route Availability 9

| locale =

| deliverydate =

| firstrundate =

| lastrundate =

| retiredate =

| withdrawndate =

| preservedunits =

| restoredate =

| scrapdate =

| currentowner =

| disposition = Two preserved; remainder scrapped

| notes =

}}

The London, Midland and Scottish Railway (LMS) Rebuilt Royal Scot Class is a class of 4-6-0 steam locomotives. 70 members of this class were rebuilt by the LMS and its successor British Railways (BR) from LMS Royal Scot Class engines by the replacement of their life expired parallel boilers with a type 2A boiler over the period 1943–1955. (The class sometimes is numbered 71 as it included a prototype 1935 rebuild LMS (4)6170 British Legion, but sufficient technical differences existed which dictate that it is treated separately). They were the second class to be rebuilt with type-2 boilers, after the rebuilding of British Legion and the Jubilee Class.

LMS gave them the power classification 6P; this was later revised by BR to 7P.