London Survey Grid - ESRI:102400

WKT

PROJCS["London_Survey_Grid", 
	GEOGCS["GCS_Xrail84", 
		DATUM["D_Xrail84", 
			SPHEROID["WGS_1984", 6378137.0, 298.257223563]], 
		PRIMEM["Greenwich", 0.0], 
		UNIT["Degree", 0.0174532925199433]], 
	PROJECTION["Transverse_Mercator"], 
	PARAMETER["False_Easting", 78250.0], 
	PARAMETER["False_Northing", -2800.0], 
	PARAMETER["Central_Meridian", -0.158333333333333], 
	PARAMETER["Scale_Factor", 0.9999999], 
	PARAMETER["Latitude_Of_Origin", 51.1666666666667], 
	UNIT["Meter", 1.0]]

WKT2

PROJCRS["London_Survey_Grid", 
	BASEGEOGCRS["GCS_Xrail84", 
		DATUM["D_Xrail84", 
			ELLIPSOID["WGS_1984", 6378137.0, 298.257223563]], 
		PRIMEM["Greenwich", 0.0], 
		CS[ellipsoidal, 2], 
		AXIS["Longitude (lon)", east, 
			ORDER[1]], 
		AXIS["Latitude (lat)", north, 
			ORDER[2]], 
		ANGLEUNIT["Degree", 0.0174532925199433]], 
	CONVERSION["Transverse_Mercator", 
		METHOD["Transverse_Mercator"], 
		PARAMETER["False_Easting", 78250.0], 
		PARAMETER["False_Northing", -2800.0], 
		PARAMETER["Central_Meridian", -0.158333333333333], 
		PARAMETER["Scale_Factor", 0.9999999], 
		PARAMETER["Latitude_Of_Origin", 51.1666666666667]], 
	CS[Cartesian, 2], 
	AXIS["Easting (X)", east, 
		ORDER[1]], 
	AXIS["Northing (Y)", north, 
		ORDER[2]], 
	LENGTHUNIT["Meter", 1.0], 
	ID["Esri", "102400"]]

Data from @esri/proj-codes

{
  "wkid": 102400,
  "latestWkid": 102400,
  "gcsWkid": 104050,
  "macro": "PE_PCS_LONDON_SURVEY_GRID",
  "name": "London_Survey_Grid",
  "wkt": "PROJCS[\"London_Survey_Grid\",GEOGCS[\"GCS_Xrail84\",DATUM[\"D_Xrail84\",SPHEROID[\"WGS_1984\",6378137.0,298.257223563]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Transverse_Mercator\"],PARAMETER[\"False_Easting\",78250.0],PARAMETER[\"False_Northing\",-2800.0],PARAMETER[\"Central_Meridian\",-0.158333333333333],PARAMETER[\"Scale_Factor\",0.9999999],PARAMETER[\"Latitude_Of_Origin\",51.1666666666667],UNIT[\"Meter\",1.0]]",
  "wkt2": "PROJCRS[\"London_Survey_Grid\",BASEGEOGCRS[\"GCS_Xrail84\",DATUM[\"D_Xrail84\",ELLIPSOID[\"WGS_1984\",6378137.0,298.257223563]],PRIMEM[\"Greenwich\",0.0],CS[ellipsoidal,2],AXIS[\"Longitude (lon)\",east,ORDER[1]],AXIS[\"Latitude (lat)\",north,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433]],CONVERSION[\"Transverse_Mercator\",METHOD[\"Transverse_Mercator\"],PARAMETER[\"False_Easting\",78250.0],PARAMETER[\"False_Northing\",-2800.0],PARAMETER[\"Central_Meridian\",-0.158333333333333],PARAMETER[\"Scale_Factor\",0.9999999],PARAMETER[\"Latitude_Of_Origin\",51.1666666666667]],CS[Cartesian,2],AXIS[\"Easting (X)\",east,ORDER[1]],AXIS[\"Northing (Y)\",north,ORDER[2]],LENGTHUNIT[\"Meter\",1.0],ID[\"Esri\",\"102400\"]]",
  "description": "London Survey Grid",
  "authority": "Esri",
  "version": "10.4.0",
  "deprecated": "no",
  "areaname": "UK - London",
  "extent": {
    "slat": 51.2,
    "nlat": 51.8,
    "llon": -0.7,
    "rlon": 0.6
  }
}