It's a strictly enforced maximum of three codeshare routes per codeshare partner. And although the KLM operation used to be run from UK crew bases, those have all been closed over those last 10-15 years and all work repatriated to the Netherlands. There was a reason for that, and it wasn't cost. The VNV would get very exercised indeed if KLM started to push the boundaries of the codeshare agreements into AMS where they believe KLM should be doing all of the flying itself.