Basically if you work in X level it job and you earn Y and you are supporting staff members and organization that earn £300 an hour, then you should receive Y. But if you are supporting people that earn £800 per hour. Then you should be receiving more than Y, not necessarily double Y but definitly more. More often than not the people earning £800 per hour are paying more for their IT support, but that is not given to the staff thanks to everyone accepting a specific market rate for a specific level.
I recruit a fair bit - and the way you're presenting it is the wrong way around.
When we recruit we have a position open to do 'function x'. Now, function x generally has a market price to it. The more general it is, the more people there are about to fulfill that role, and typically this drives down the costs of that role. By costs, I mean salaries & benefits.
The opposite of that is that more specialised skills means a reduced pool of people to recruit from, and typically this drives UP costs, so salary/benefits. Somebody with more specialist skills typically gets paid more than a generalist.
The idea that you should earn more because other people in your organisation too is a bogus one, and doesn't work. It's not about the person you're recruiting, it's about the position you're filling.
We work in multiple sectors for example - from banking, to insurance, to retail. We'll often move people from one sector to another as well due to project constraints. Those people will get a package based on the general offering for their function, and how hard it is for us to fulfill the role.
The only time sector affects pay is when there's specific skills in that sector that are more specialised - does that make sense? Somebody with back-room banking IT for example is worth more to us than somebody who isn't, and is also harder to recruit. As they're harder to recruit we offer a better package.
Business is not generally altruistic in nature. You need to be competitive, and you do that by paying your staff what you can recruit staff for to fulfill a function. What you don't do is over-pay to be 'nice' - if you do that, you're not competitive. That's the nature of a free market.
The idea that people get paid what they ask for is an interesting one too - in some respects it's true.
We recruit for position X, that requires certain skills. We get people in and we think somebody has those relevant skills, and asks to be paid 10,000 pounds (keeping the maths simple). Our budget may be up to 20,000 pounds however, and as we believe they can do the job, we *would* have been willing to pay more. The fact they asked for 10k means they get paid 10k.
Conversely, we get people asking for much more than is in budget. That takes some justification, but DOES happen. More often than not people are recruited above budget when they offer additional skills that could benefit either the specific job or the organisation as a whole. Then it's a management judgement call as to whether they're worth the investment.
What you need to be aware of is that recruiting is generally by function, not by people. I know it's a little difficult to separate.
It's similar when you get people wanting to be paid way beyond the normal pay point for functions simply because 'they've been here for 10 years'. Sometimes it's worth paying more due to experience, sometimes it isn't. You just have to remember you're paying for a functional role, and not a person.
You want to earn more? Ignore what everyone else is earning - just get out there and skill up in to a more specialised area that fewer people can fulfill, and the wages/packages will rise with it.
That's what your solicitors at 800/hour + have done.