This must have been the Rotterdam flight pushing back at LHR as I don't think KLM/NLM used CityHopper on AMS services. I also noted two KLM flights on the same afternoon. This was taken prior to T4 being built.  All KLM/NLM services migrated to T4 once it was operational.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/130275500@N02">G B_NZ</a>
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<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/130275500@N02/23450245914/">KLM CityHopper F-28-4000 PH-CHF at LHR</a>