Worst popularity ratings for all leaders of opposition since 1978

Corbyn is managing to please almost none of the people all of the time.  The left liberal proportion of the population, who are his natural supporters, are nearly all remainers - his ludicrous stance on brexit is alienating all those people.   The working class brexit vote are decamping to UKIP because he is not being clear enough for them either.

the left liberal proportion of the population, who are his natural supporters, are nearly all remainers 

Plus they are mainly middle class southerners who, whilst enjoying the idea of a bit more socialism as it is the right thing to talk about at dinner parties, don't really fancy the idea of paying 50% on income above £80K or having to pay VAT on little Arabella and Theo's school fees.

Wellers if you send your kids to private school you could conceivably still be a labour supporter but you are unlikely to be in the Corbyn wing of the party (unless you are Diane Abbott of course)