PoP wrote:
SWMBO went off to work this morning, happily thinking about the new
stainless steel 1.5 bowl sink I was going to fit to replace the yucky
white plasticky thing that's been bugging her for a while.

Old plasticky thing wouldn't release from the worktop because of the
sealant which was sucking it down, but soon sorted that with a car
jack which was able to exert enough pressure to release the sealant
around the edges. Everything going according to plan.....

Before doing anything naughty with the plumbing arrangements I thought
I'd just drop the new sink into the hole in the worktop to make sure I
didn't need to do any cutting. That's when it became apparent that the
old hole wasn't suitable for the new sink. And yet these sinks have
the same vital dimensions - it's the radius on the corners which is
different and I couldn't find a suitable position where the new sink
would cover all the hole. Whoever fitted this original sink was a bit
too generous with his hole cutting and upon inspection it showed that
the old sink sits precariously on the edges of the hole underneath.

You could do what an accquaintance of mine did, leave holes around the edge.
Nice it is not but goes well with the rest of his DIY quality :-)