In message , Andrew Gabriel
writes

If you have a ribbed rubber seal that maybe isn't sealing quite as
well as it did when new, as you pull it out, each ridge flicks ****
in your face as it pops out of the pipe...

Thank you Andrew, I will look forward to that :-)

Here are three photos :

http://www.binnsroad.co.uk/misc/wc/index.html

It looks to me as though the white part is an offset rubber (?)
connector, which is probably (?) just plugged into the grey waste pipe.

Next job (!) is to just pull that white connector off the grey pipe?
That should, by the looks of it, leave the top of the grey waste pipe
just below floor level, which is handy. Then just pop in a stopper?
Something like eBay 251278942890

http://www.ebay.co.uk/itm/110mm-4-So...ng-Cap-Stop-En
d/251278942890?epid=1932237304&hash=item3a816462aa:g :k9sAAOSwB-1Y7kTL

Just push in, perhaps with a little washing up liquid to lubricate?
--
Graeme