During those first couple of NSE days (June/September 86?) the SW borrowed a fair few DEMU's from New Cross Gate ('The Gate' to some of us) which were booked spare at weekends. Must try and dig out my old pics, but have images of a couple of 6D formations at Poole/Bournemouth, they having been used on additional Bournemouth-Weymouth shuttles, and also captured a 12H on the Up SWML on its way home to NXG after proceedings had finished.
Such borrowing of stock from a neighbouring Division was so easy back then, a simple phone call from a planner in one Divisional office to (what was normally) a 'mate' in another Divisional office, and that was that.
That's the sort of simple co-operation that I suspect is missing these days, and many younger planners of todays railway (I suspect) can only dream of !
Rose tinted to a degree on my part perhaps this far down the line, but it did seem so much simpler back then.