It's the 'Islington Elite' mindset. Everyone should be in their box. Doing well for yourself is frowned upon. The proletariat should stay the proletariat at all times, but be comfortable. Nobody should be allowed to be 'super rich', but being well off is fine as long as you're 'one of us' in the first place.
In one way, it's an admirable goal, because it takes off the excesses in terms of the excessively rich and the excessively poor in society. That's what appeals to people - the 'Robin Hood' mentality of robbing the rich to feed the poor. However, if you just follow the logic to the end point of such a system, you begin to see what a dystopian nightmare it probably leads to. A societal segregation, where some are more equal than others. Business and enterprise is the enemy, so society as a whole flounders and we all race to the bottom, except - of course - for those who are more equal than others.
The far left is different to the far right in that, in general, its' advocates are genuinely pushing for a fairer society. The far right aren't - even if you take out the true far right (e.g. nazis) and just focus on the economical far right, they are looking for the opposite of fair; they want a society where people eat other people to climb the ladder, all who fall off that ladder are acceptable losses.
For me, there's a middle ground between the two, one where you can show restraint, cherry pick the best of all worlds. That, apparently, makes me a 'spineless centrist'. So be it. But I truly believe the vast majority of people in this country feel that way - they want what's best for their families, are happy at whatever creates a fairer world as long as it doesn't make their own world worse in the process. There's an inherent selfishness and aspiration in the average UK citizen, but also an inherent desire for degrees of equity.
The Tories, for much of modern society, have been closer to that viewpoint than Labour. When Labour have been closer, like in 1997, they've won elections easily. When they've been leftist idealogues, they get trounced.