A class 90, 90039, found itself at Llandudno Junction after being dragged as far as there in the consist of a Holyhead service in June 2005, before someone realised that class 90s are, unsurprisingly, not cleared for the North Wales Coast route! EWS/DB class 90s have also turned up at off wires locations such as Thornaby and Toton for tyre turning or repaints.
Also for a short period in the early 2000s Valley Lines branded, though not liveried, class 142s could be found operating on North East services from Heaton depot after Arriva Trains Northern did a straight swap with a batch of their own units. Never did work out what benefit swapping one batch of 142s for another bestowed on either operator.