That does seem mad, that clash, but we don't know when the show organisers booked the venues, nor if either's competitor was confirmed at the time they did.
The Harrogate model-engineering exhibition is still not on the YEC web-site, which now lists five other events (one is trade-only) from February to October. These include March 17-19, a motor-caravan show*. I looked at the YEC site for this reply, this very afternoon, Friday 6th of January – very late for confirming, advertising and planning for, a major exhibition.
Whereas Meridienne's site already shows two model–railway and one model-engineering, exhibitions for Warwickshire in 2023, the last being "ours" in October.
It became fairly clear to me when I telephoned the YEC a while back that it is rather at the mercy of the event organisers. Sensibly, it does not advertise events not yet confirmed, so one draws one's own conclusions.
Midlands has a good track(!) record with visitors, exhibitors and traders so it's very likely its shows were being booked as the cleaners were sweeping up after the previous ones. If so, one might ask if the Yorkshire show organiser looked at what other exhibitions were already in the offing.
Whereas poor YEC is yet to be tried and tested for our related hobbies – everyone knows it's a fine venue physically and easy to reach, from the East anyway; but traders and club-stand secretaries carting very heavy goods about, will be nervous of something yet to be formally publicised by anyone anywhere.
So although we now seem to have this unfortunate clash, don't blame the exhibition-centres. It must be very frustrating for them having to hold days on spec like this. Instead ask if the show organisers have run into difficulties, encouraging the stands people to plump for the known instead..
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*(Motor-caravan show – where you can establish if any of the new offerings suitable for the rally-site home, can internally accommodate your 4" -scale road-locomotive.)