I didn't think lawyers would defend a libel case on a no-win no-fee 
Maybe any lawyers here, could correct me on this.
Damages would not normally be awarded to the defendant in a libel case, just their costs, which their client would otherwise have to pay.
So, no chance of a large payout to lawyers who successfully defend: they just get their usual fee.
No-win no-fee makes financial sense for lawyers only where they have a decent chance at a % of large damages.
Usually when suing a large firm or public body for injury
Monroe's lawyer was quoted, e.g.
http://www.huffingtonpost.co.uk/entry/katie-hopkinsdefeated-by-jack-monroe-in-libel-caseukk_58c28bf5e4b054a0ea69df05
"“The price of not saying sorry has been very high.
Hopkins has had to pay out of her own pocket a six figure sum in damages and costs
for a tweet that should have been deleted within minutes as soon as she was told it was wrong.
On this occasion, the cost of renting that gob was particularly high."