There's some interesting detail in this piece in The Guardian, especially views of Chuka Umunna and Paul Myners. Being someone who is a Labour supporter, interested in corp gov and interested in language/communications I think there are a couple of shifts in message going on.
For example Labour is starting to talk (as Chuka has done) about "rewards for failure and excessive pay", ie there are different problems here. The Tories in particular want to try and hold the debate back to rewards for failure and conflate that with excessive pay. It's important that Labour makes the difference explicit as the Tories are uncomfortable with the notion that top pay might represent (to a greater or lesser extent) rent seeking rather than an optimal market outcome.
Also the language on bonuses seems to be becoming a bit more explicit - ie Rachel Reeves using the line that bonuses are something that should be awarded for really exceptional performance, for everything else you get your salary. This is potentially important as any fule no that the explosion in performance-related reward is behind much of the growth in top pay. I hope we hear more on this. Most working people are expected to turn and do their job for their salary, they can't hope for multiples of salary to do it better. So performance pay of this size is unique to certain bits of the economy.