Decided to open up the dodgy hub, and found inner bearing completely shot. The lip seal was long gone, and the bearing was filled with a sandy smergel paste (the turdlike goo at the bottom of the pic). Luckily it's standard bearings (6204 and 6205), available at our local el cheapo car supply chain. £8 for the two of them!
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A minor setback when I bought the wrong seal - I stupidly assumed the same inner diameter as the inner bearing, not realizing that it would in fact be riding on a shoulder next to bearing. Upon assembly the seal was then squashed between the bearing and said shoulder.
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Got new ones today, bicycle delivered 40 km (one way) by a mate, and now all is good.