Either that or the mixer/router doesn't have enough sources to cope with such an unusually news filled programme?
Even if the mixer has run out of spare inputs (which is unlikely) surely the station router has capacity, and could be used to pre select ? Does anybody know what kit they do have there, their set up makes Channel TV look like CNN in comparison !
I think you're making a pretty wild assumption that there is a 'station router', and that destinations from it land on a mixer. I wouldn't be surprised if it were just a couple of FCPs or News Cutters, 3 brick cameras and a simple GVG100-style vision mixer (hopefully digital) with hardwired inputs (which is similar to what BBC Cambridge had in the early days - though they were Ikegami industrial cameras, not bricks) If they don't have a Magic Dave or similar I doubt they have any way of synchronising remote sources and need to genlock (presumably there is a synchroniser in Plymouth before the opt-switch or in the link from JY to PY)?
BBC Jersey is a TINY operation - it's not like the other sub-regions in Oxford or Cambridge (Cambridge now has pretty much the same facilities as a full region in lots of ways). It has a tiny studio, tiny gallery, and very limited TV facilities. It was an upgrade to the single camera in the IBA garage after all...