My personal view is a refurbishment should be as done in BR days or by London buses and others in pre privatisation days I.e. complete stipdown with all mechanical components reconditioned, interior refreshed and full repaint. Northern just do the last 2. May be mixed up with the complexities leasing of.
K
Surely “refurbishment” of mechanical components is called an overhaul, not a refurbishment. A refurbishment is about updating the interior - literally the furnishings, as the word would suggest