The White plastic ring has to have a gap in it so that when you reinsert it it closes up and it doesn't hold back the water,that is the job of the o rings.the job of the plastic ring is to act as a bearing so that the tap doesn't judder when turned.also it stops the tap from shaking form side to side.Bob.
Just a quick update on this (just in case someone finds this thread with the same type of tap as me - quite a long shot but you never know!).
After a bit of googling I managed to find the exact type of tap that I have at "Inderkitchen" it's a "Paini Cox Spring Side Lever Monobloc Kitchen Mixer Tap - Tap Finish:Chrome"
I bought it, just fitted the spout part (i.e left the base in place) and now everything is sorted again.
Wife is happy. Which obviously means that I am happy as various husbandry privileges are now fully restored.
Thanks again for everyone's help. Now... just sit back and wait for the next thing to break........
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