PF
KLM are the only regional operator from UK regional airports who have a codeshare agreement with anyone in AMS, i.e themselves and KLM are not going to operate from CAX when the local catchment area is more than adequately served from Newcatle.
Even if another operator was persauded to operate to AMS from CAX, they wouldn't get any interline agreement and KLM would destroy them by lowering fares - they've done it with Flybe and a few others.
By the way, Easyjet, Ryanair et al, require a runway with a LDA, ASDA, TORA of at least 1950m - which is why you'll never see them in CAX.