It worked better than I expected, and at least as well as I'd expect any off the shelf abrasive cleaner to work. The scrubbing with the lemon and sea salt was very satisfying, and I left the sink covered in the juice for a couple of hours then rinsed it with water. There's still some
ingrained discolouration deep in the pitted plastic, so after tonight's load of washing up, I'll have another go with the lemon & salt & leave it overnight.
The lemony smell was a nice change to Mr Muscle, and far far better than bleach which I'd usually use.
Thanks, now I'm a convert and I'll be picking your brains for more info in the future.
Cartoon from climatecartoons.org. Click on the picture to enlarge.