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Job done, now perfect. After scraping out all the sealant that I could, I tucked lots of toilet paper into the gap between shower tray and tiles, poured bleach along bottom of tiled walls which then soaked into the paper, left for a couple of hours and hey presto - perfect job.
I was interested in Fanriffic's DIY Donny which suggested a multi-purpose solvent remover from CEF but unfortunately, this is not now available, probably because it might contain a chemical not suitable for home use.
Thanks everyone - trish.