This is construction grade one part, fast curing, bacteria-resistant silicone that provides excellent adhesion to most non-porous surfaces including ceramics and porcelain. Mould-Resistant Water-Resistant For Use on Baths, Showers, Basins & Sanitaryware. Also great for kitchens. Contains Fungicide to Resist Mould Growth Fast Cure - Tack Free in 30 Minutes Joint Movement Capability: +/-20% These are going for £9 in Toolstation and £10 in Screwfix. I'm doing them for £3 each or if you take all 12 I'll do them for £30
eBay