Living wage - a factual calculation of an indicative figure for an annual income requried by a person based on their family situation (single, part of a couple, with out kids, with 1 kid, 2, 3...) to have the minimum 'acceptible' quality of life.
You can argue over what the minumum acceptible quality of life is (from absolutely nothing, to palaces and riches) - or about whether certain family situations should be 'permitted', or how detailed/general the different groups should be, and even where the 'wage' should come from (who pays it) but the principle of a 'Living Wage' is fact, not opinion.
Having said that, Living Wage is oriented to 'earnings' - so excludes in-work benefits etc - I'd rather see a 'Living Income' so the division between benefits and earnings is more transparent. I would especailly like this as in-work benefits are often related to income - so vary one and the other vairies too.
The Living Wage Foundation are the good/bad guys here... they are a charity that have claimed the 'Living Wage' mantle - they calculate a figure and then get grants from government to promote it and income from employers who want their acreditiation.
The Living Wage Foundation calculation arrives at two figures - one for London and one for the rest of the UK.
To arrive at the figure, figures are calculated for various different family situations (which obviously vary hugely - in 2014 from £5.70 for a member of a couple, £8.30 for a single, through a whole range up to £21.10 for a single parent with three chidlren) these indivdiual figures are weighted and averaged (in 2014 to £9.20) and then it is adjusted so acredited employers aren't asked for to pay too much of an increase - in 2014 the adjusted figure was £7.95 (a reduction of £1.35).
As you can see the final published 'Living Wage' is insufficient for every class of family member except a member of a childless couple. However despite this, the 'acredition' will give employers a solid excuse to pay this low figure, and indeed to boast about it.
So really they are just selling indulgnces like the medieval roman catholic church.