OSGB 1970 (SN) - EPSG:4278

WKT

GEOGCS["GCS_OSGB_1970_SN", 
	DATUM["D_OSGB_1970_SN", 
		SPHEROID["Airy_1830", 6377563.396, 299.3249646]], 
	PRIMEM["Greenwich", 0.0], 
	UNIT["Degree", 0.0174532925199433]]

WKT2

GEOGCRS["GCS_OSGB_1970_SN", 
	DATUM["D_OSGB_1970_SN", 
		ELLIPSOID["Airy_1830", 6377563.396, 299.3249646]], 
	PRIMEM["Greenwich", 0.0], 
	CS[ellipsoidal, 2], 
	AXIS["Latitude (lat)", north, 
		ORDER[1]], 
	AXIS["Longitude (lon)", east, 
		ORDER[2]], 
	ANGLEUNIT["Degree", 0.0174532925199433], 
	ID["EPSG", "4278"]]

Data from @esri/proj-codes

{
  "wkid": 4278,
  "latestWkid": 4278,
  "macro": "PE_GCS_OSGB_1970_SN",
  "name": "GCS_OSGB_1970_SN",
  "wkt": "GEOGCS[\"GCS_OSGB_1970_SN\",DATUM[\"D_OSGB_1970_SN\",SPHEROID[\"Airy_1830\",6377563.396,299.3249646]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]]",
  "wkt2": "GEOGCRS[\"GCS_OSGB_1970_SN\",DATUM[\"D_OSGB_1970_SN\",ELLIPSOID[\"Airy_1830\",6377563.396,299.3249646]],PRIMEM[\"Greenwich\",0.0],CS[ellipsoidal,2],AXIS[\"Latitude (lat)\",north,ORDER[1]],AXIS[\"Longitude (lon)\",east,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433],ID[\"EPSG\",\"4278\"]]",
  "description": "OSGB 1970 (SN)",
  "authority": "EPSG",
  "version": "6.5(3.0.1)",
  "deprecated": "no",
  "areaname": "UK - Great Britain onshore and nearshore; Isle of Man",
  "extent": {
    "slat": 49.79,
    "nlat": 60.94,
    "llon": -8.82,
    "rlon": 1.92
  }
}