When will Labour make a come back?

[Filuwaúrdjan]

It's impossible to tell at this stage - which is usually the case. Interestingly there tends to be no relation to the "success" of the previous government of the party in question; the greatest Liberal government was also the last, pointing to real achievements* from the various Baldwin governments is rather hard and yet the Baldwin-led Tories record at coming back from defeat speaks for itself, after the Attlee government lost office in 1951 Labour didn't win another General Election until 1964, and Labour was back in power less than four years after the defeat of the 1964-70 Wilson government - which was generally regarded (on both the left and the right) as an abject failure until the early '90's or so.

It depends on a range of things that we don't know yet - to name but a few, the result of the 2010 election, the policies and popularity of the new government, the economic situation, the reaction of Labour to the defeat (both in terms of the new leadership and internal issues - when Labour loses an election there's usually a civil war or instability shortly afterwards). We don't know the answer to any of these questions yet** and until we do it's impossible to answer your question with any degree of accuracy.

*You still sometimes see them getting the credit for increased subsidies for council house construction, but the relevant legislation (the "Wheatley Act" and the "Greenwood Act") were passed by the MacDonald (Labour minority, not National) governments.

**Yes, it's possible to guess. But that's all. Admittedly when such questions are answered guessing answers half the question, confirmation bias the rest.

[Filuwaúrdjan]

The Tory plans to cut the number of Commons seats may slow Labour's return to power down too

That would only be the guess if they took a leaf out of Sarkozy's book and played at gerrymandering. Simply reducing the number of constituencies would just increase volatility and (as a percentage of seats) electoral turnover. Just as Labour supporters are wrong to assume that AV would always help them, Tories are wrong to assume that cutting the size of Parliament will be to their advantage all the time. As far as vote percentages go, LibDems are actually wrong to assume the same about STV - they'd win more seats though, even if their vote seeped sharply away in places, so it's not quite such an irrational hope.