Tornado

You misunderstand, the clipped siding was always in location, but out of use, what you have seen is track being run to that point.

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I suspect, when thought was taken to the mainline connection in the 2000's, and prices quoted, it may have then had a consideration in a redundant siding connection over the road being used instead.
If long term planning was to use the new site, because of the low cost mainline connection re-activation, that makes complete sense, and what you saw.
Remember that connection was to a lifted 500m siding, and that could provide stabling and servicing for a mainline rake, a milepost in the successful council grant application.
So for the trust another milestone passed, box ticked, and potential funder, no doubt happy, as they host an event for S&D200.
On that point alone they deserve praise.