A couple of good posts here about the state of Labour in the UK.
http://chocolateandvodka.com/2015/07/21/labours-already-dead-but-who-killed-them/
http://simonnricketts.tumblr.com/post/124334692582/youre-already-dead
Labour's dead now and we probably have to suffer the full 13 years of Tory mis-rule. So it's time for Labour to remember what it's actually about and to pull the Overton Window[1] to the left. They need to find some spine and create an opposition party that’s actually in opposition to the Tories. Maybe real Left Socialism is unelectable in this part of the election cycle. But that doesn't mean the reasons for it and need for it have disappeared.
The Farage/Trump deal seems to be recognising that it doesn't matter if you get elected or not, if you can say what others dare not say and so pull the conversation your way. The Left should understand that they can play that game as well.
Meanwhile it's the SNP that are standing for 20th century, mixed social-democracy in the UK not Labour. If the current Tories are Blair-Lite[2], then current Labour is Blair-Lite-Lite. To the point where there's nothing there at all.
[1]https://en.wikipedia.org/wiki/Overton_window
[2]Cameron vs Brown was described as Blair-Lite vs Thatcher-Lite
In my opinion, the only true leftist party that has any (tiny) share in the light is the Greens. Honestly, they're a bunch of amateurs who didn't realise their time could have come. They played the little outsiders, and were treated as such. But their policies are genuinely more left wing than Labour or the Liberals, easily. Labour don't seem to want to change the conversation, and I think it will take a party such as the Greens to move the conversation on. That, in itself, may take at least 2 election cycles.
Labour haven't just died anyway, they died when Tony Blair took them right, called them New Labour, and did whatever he could to win the election (those are his words by the way).