Not on pilgrimage to Canterbury but Tonbridge West Yard is close enough. This is the High Speed Milling Train, used to cut defects out of the railhead before they become problematic. 66728 and 66768 were bringing the miller from Bescot as 6X69 on 6 February 2023 and were photographed east of Hook on the South Western Main line.
PHOTO DATA FOR IMAGE 23-D-0044
camera : Nikon D610
lens : 70-200mm f/2.8
focal length : 70.0 mm
shutter : 1/800 sec
aperture : f/8.0
ISO : 320 ISO
original : Digital: 24MP NEF
SUBJECT DATA
Loco / Unit : 66.728 top n tail with 66.768
Train : 6X69, 03:54 Bescot Up Engineers Sdgs - Tonbridge West Yard departmental