TfL has recently confirmed a tender to replace its 29 ageing battery engineering locomotives: some of this indefatigable yellow fleet have components over 100yrs old. They’re not seen often (usually operating away from public services) so here are my snaps of L52 under repair at Ruislip Depôt, L27 & a consist of 6 locos readying for the night shift there, plus L48 on duty at Bank during the rebuild project. New locos are due at design stage in 2029.