LiDaR.py

import bpy  

dfile = r"C:\Users\dealga\Desktop\Archive\SU8606_DSM_1M.asc"

getval = lambda i: next(i).split()[1]

with open(dfile) as ofile:
    ncols = getval(ofile)
    nrows = getval(ofile)
    xllcorner = getval(ofile)
    yllcorner = getval(ofile)
    cellsize = getval(ofile)
    NODATA_value = getval(ofile)
    
    print(ncols, nrows, xllcorner, yllcorner, cellsize, NODATA_value)

    # this will read the rest
    verts = []
    add_vert = verts.append
    for i, row in enumerate(ofile):
        for j, coord in enumerate(row.split()):
            x = j * 0.01   #   cell x width
            y = i * 0.01   #   cell y width
            z = float(coord) / 20
            add_vert((x,y,z))
            
    print('done')
    print('last vertex:', verts[-1])


# do your own error handling
  
mesh_data = bpy.data.meshes.new("LIDAR_mesh_data")  
mesh_data.from_pydata(verts, [], [])  
mesh_data.update()
  
LIDAR_object = bpy.data.objects.new("LIDAR_Object", mesh_data)  
  
scene = bpy.context.scene    
scene.objects.link(LIDAR_object)    
LIDAR_object.select = True        

To get this to work in Blender 2.8+ replace

scene = bpy.context.scene
scene.objects.link(LIDAR_object)

with

bpy.context.collection.objects.link(LIDAR_object)