Was the exchange still in use and, if so, we're there any ill effects?
I would
assume that a BT exchange would have pretty effective lightning protection?
I would also
assume that good lightning protection would be enough enable such a building withstand a direct strike. After all, buildings like the worlds' giant skyscrapers are
presumably struck on a regular basis, yet are able to continue business as normal, unnoticed by users of all the computers and IT apparatus inside.
But these assumptions and presumptions are open to challenge. If anybody can share authoritative knowledge about BT exchanges and their lightning protection, I'd be all ears.