So that's what Thursday's footbridge closure was about:

Wolfeeboy’s blog:

I had a phone call from a friend, Ben Coe, this week, informing me that a photo op would be presenting itself today, (Thursday), with the Footbridge being opened to allow what will be the latest riverbank houseboat through, at around midday ish, so I hot tailed it along there. Armed with cameras and note book to witness and document what could prove to be one of, if not, the, last occasion of this Footbridge opening before it is replaced later this year, I set myself up and awaited this historical moment to unfold. Alas, after snapping away at wildlife for a bit, chatting to Gav, who had also come along to witness the momentous event, I checked my phone and spotted a new message, from Ben, it had all been postponed until Friday now.