SECR Q1 class

{{distinguish|SR Q1 class}}

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

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

{{Infobox locomotive

|name = SECR Q1 class

|powertype = Steam

|image =

|caption =

|designer = Harry Wainwright

|builder =

|serialnumber =

|builddate =

|totalproduction =

|rebuilder =

|rebuilddate = 1903–1917

|numberrebuilt = 55

|whytetype = 0-4-4T

|uicclass = B2′ n2t

|gauge = {{RailGauge|ussg}}

|driverdiameter = {{convert|5|ft|6|in|m|3|abbr=on}}

|trailingdiameter=

|length =

|height =

|axleload =

|weightondrivers =

|locoweight = {{convert|49.6|LT|1}}

|fueltype = Coal

|fuelcap =

|watercap =

|boilerpressure = {{convert|150|lbf/in2|MPa|2|abbr=on}}

|cylindercount = Two, inside

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

|valvegear = Stephenson valve gear

|tractiveeffort = {{convert|16274|lbf|kN|2|abbr=on}}

|operator = {{ubl|South Eastern and Chatham Railway|→ Southern Railway}}

|operatorclass = Q1

|powerclass =

|nicknames =

|withdrawndate = 1909–1930

|numinclass = 1 January 1923: 47

|disposition = All scrapped

}}

The SECR Q1 class was a class of 0-4-4T steam locomotives of the South Eastern and Chatham Railway. The class was rebuilt from older Stirling Q class locomotives by Harry Wainwright between 1903 and 1917 by fitting the boiler that had been designed for the H class 0-4-4T in 1902–03.Casserley, H.C. and Johnston, S.W., Locomotives at the Grouping 1, Southern Railway, page 42, Ian Allan, 1974, {{ISBN|0-7110-0552-4}}{{cite book |last=Bradley |first=D.L. |title=The Locomotive History of the South Eastern Railway |edition=2nd |date=September 1985 |orig-year=1963 |publisher=RCTS |location=London |isbn=0-901115-48-7 |oclc=642415860 |page=165 }}