Not dim at all, John

Here’s the wiring diagram for that bit of the car:
E0BB2D8D-57E9-45D2-87D4-39985CF0E7C7.png
The pump is the bit at the top of the diagram. For the pump to work normally on the car, three things must be true:
1. Ignition is off (sensed by the cooling fan relay)
2. The cooling fan temperature switch is closed (ON). Note: this switch is specific to the fans; it’s a different switch from the one driving the temp gauge and the one sending info to the ECU
3. Fuse C4 is sound
The “earthing trick” that you refer to just gets over the hassle of needing the cooling fan temperature switch on (just a thought: you are earthing the right switch, aren’t you? It’s the red one in this diagram. There are three of the b***ers):
9D5B41FE-1B45-47BB-98CA-C2E05CBC7817.png
From the symptoms you describe, I’d be inclined to suspect that either you have a bad earth (often an issue on the Elan), or the fuse has blown, or you have a faulty cooling pump relay. Both these last two are under the removable cover on top of the dashboard in front of the steering wheel, and both are cheap to replace. You can find details of exactly where they are in the Electrical Manual, which is available through the “Manuals” link at the top of this and all the forum pages, assuming you’re logged in.
If you’re coming to Castle Combe at the end of May, I’m happy to have a look (assuming you’ve not fixed it by then), or there may be another more local member who could give you a hand.
Hope that helps!
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