Merit but 'no'- 18 firms refused v strong case, why won't any take big public interest ones in England (unless it's a group claim?)

Really strong, very evidenced case-'merit' oft mentioned- but 18 firms 'at capacity' - it's way meaty and public interest- is there a firm left in England that would take such a case? Also- how common is it for sols to share evidence of potential clients- they take huge amounts of it - as I said-very, very powerful stuff-also- how much evidence does one actually reasonably need to impart? I have some legal exp and years ago won a big case- it used to be that solicitors took cases on merit and that interesting cases were a healthy challenge- now seems they only take easy and cheap ones? Thanks for any tips here

Location:England