GBK19 Grid - EPSG:9456

WKT

PROJCS["GBK19_Grid", 
	GEOGCS["GBK19-IRF", 
		DATUM["GBK19_Intermediate_Reference_Frame", 
			SPHEROID["GRS_1980", 6378137.0, 298.257222101]], 
		PRIMEM["Greenwich", 0.0], 
		UNIT["Degree", 0.0174532925199433]], 
	PROJECTION["Transverse_Mercator"], 
	PARAMETER["False_Easting", 93720.394], 
	PARAMETER["False_Northing", 113870.493], 
	PARAMETER["Central_Meridian", -4.35], 
	PARAMETER["Scale_Factor", 1.0], 
	PARAMETER["Latitude_Of_Origin", 55.75], 
	UNIT["Meter", 1.0]]

WKT2

PROJCRS["GBK19_Grid", 
	BASEGEOGCRS["GBK19-IRF", 
		DATUM["GBK19_Intermediate_Reference_Frame", 
			ELLIPSOID["GRS_1980", 6378137.0, 298.257222101]], 
		PRIMEM["Greenwich", 0.0], 
		CS[ellipsoidal, 2], 
		AXIS["Latitude (lat)", north, 
			ORDER[1]], 
		AXIS["Longitude (lon)", east, 
			ORDER[2]], 
		ANGLEUNIT["Degree", 0.0174532925199433]], 
	CONVERSION["Transverse_Mercator", 
		METHOD["Transverse_Mercator"], 
		PARAMETER["False_Easting", 93720.394], 
		PARAMETER["False_Northing", 113870.493], 
		PARAMETER["Central_Meridian", -4.35], 
		PARAMETER["Scale_Factor", 1.0], 
		PARAMETER["Latitude_Of_Origin", 55.75]], 
	CS[Cartesian, 2], 
	AXIS["Easting (X)", east, 
		ORDER[1]], 
	AXIS["Northing (Y)", north, 
		ORDER[2]], 
	LENGTHUNIT["Meter", 1.0], 
	ID["EPSG", "9456"]]

Data from @esri/proj-codes

{
  "wkid": 9456,
  "latestWkid": 9456,
  "gcsWkid": 9453,
  "macro": "PE_PCS_GBK19_GRID",
  "name": "GBK19_Grid",
  "wkt": "PROJCS[\"GBK19_Grid\",GEOGCS[\"GBK19-IRF\",DATUM[\"GBK19_Intermediate_Reference_Frame\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Transverse_Mercator\"],PARAMETER[\"False_Easting\",93720.394],PARAMETER[\"False_Northing\",113870.493],PARAMETER[\"Central_Meridian\",-4.35],PARAMETER[\"Scale_Factor\",1.0],PARAMETER[\"Latitude_Of_Origin\",55.75],UNIT[\"Meter\",1.0]]",
  "wkt2": "PROJCRS[\"GBK19_Grid\",BASEGEOGCRS[\"GBK19-IRF\",DATUM[\"GBK19_Intermediate_Reference_Frame\",ELLIPSOID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],CS[ellipsoidal,2],AXIS[\"Latitude (lat)\",north,ORDER[1]],AXIS[\"Longitude (lon)\",east,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433]],CONVERSION[\"Transverse_Mercator\",METHOD[\"Transverse_Mercator\"],PARAMETER[\"False_Easting\",93720.394],PARAMETER[\"False_Northing\",113870.493],PARAMETER[\"Central_Meridian\",-4.35],PARAMETER[\"Scale_Factor\",1.0],PARAMETER[\"Latitude_Of_Origin\",55.75]],CS[Cartesian,2],AXIS[\"Easting (X)\",east,ORDER[1]],AXIS[\"Northing (Y)\",north,ORDER[2]],LENGTHUNIT[\"Meter\",1.0],ID[\"EPSG\",\"9456\"]]",
  "description": "GBK19 Grid",
  "authority": "EPSG",
  "version": "9.9(12.8.0)",
  "deprecated": "no",
  "areaname": "UK - Glasgow to Kilmarnock",
  "extent": {
    "slat": 55.55,
    "nlat": 55.95,
    "llon": -4.65,
    "rlon": -4.05
  }
}