Dave Osler thinks that there are a number of reasons why a Labour / Lib Dem merger is likely to happen in the medium term.
I'm not sure that some of the historic reasons why they should never have been the same party are as ahistoric as he thinks, indeed, my recollection of Paul Addison's very good 'Road to 1945' (now sadly out of print) is of a period in the middle of the century when there was almost a consensus between the non-Guilty Men tories (notably Macmillan) and plenty of Liberals in support of the defining contours of the post-1945 settlement.
I don't have the book to hand any more, so I may be corrected on a few details here, but Macmillan was advocating - in the late 1930s - policies somewhat more radical that those implemented after the war by Labour. Policies that were clearly in the 'state socialism' mould as well - not just the kind of stuff that you could have expected a bit of consensus on.
I mention this in order to make the point that ideological consensus and political alliance don't always go hand-in-hand.
The post-war Labour government can almost be seen as a spectacular triumph of political entryism of the kind revived in the 1980s by the Revolutionary Socialist League (AKA Militant Tendency) In this case, Labour was effectively hi-jacked by Liberals - Beveridge, Keynes, and even a young Harold Wilson.
On Dave's logic, surely the alliance that is the Labour Party (organised Labour, co-ops, the odd god-botherer and, notably, the Fabians) couldn't have happened. But it did. And it could easily have encompassed large slices of the Liberal Party at that time.
If it quacks like a duck and waddles like a duck, it's probably a duck. On this logic, the Fabians were Liberals.
I have a theory on why it didn't happen formally then - and why it won't now. It's a reconfiguration of my 'why Fianna Fail won't succeed in Northern Ireland' post the other day.
One word; bureaucracy. As Parkinson's Law explains, bureaucrats recruit subordinates, not rivals.
Labour has a bureaucracy, so do the Lib Dems. MPs everywhere would have to reapply for their jobs. Researchers would be laid off, local organisers would have to compete for a single job, and animosities - often decades old - particularly in the north west, where the Liberals sometimes were surrogates for the Tories - would make the actual wedding a bloodbath.
There may be no reason for the two ideologies, as far as there are any these days, to merge. I don't have a strong view either way.
But the people? Never.