Once you are a QC do you carry on in same chambers but charge a higher fee and get hired for better work? Or does your work change in other ways?
Like all things it depends. The ideal would be you are already in a chambers that is working for you and your practice continues to grow as you become more senior.
But taking silk is a big risk because you are moving from being at the top of your tree (top of the senior junior barristers) to being the bottom run of the next tree (most junior of the silks).
Becoming a QC is sort of like becoming a consultant in a medical sense. So if you have a serious complicated medical problem, you are going to want to see the top most senior person you can find. The same is true if you have a serious complicated legal problem. You aren't going to want a baby QC; you will want a senior QC who has been leading in difficult cases for years.
For this reason it can take several years to get going in silk and income usually takes a dip.
This can cause new silks to panic and then move chambers thinking they will have a more supported practice elsewhere.
If Barristers are asked for QC application references are they happy to provide them? Do you owe them a favour afterwards?! Does it negatively affect your reputation if you recommend someone and they aren't successful?
Taking those one at a time:
Like all reference requests it depends. There is a real issue with barristers at a certain level of seniority (ready to apply to become a QC) being against barristers of the same level in same area of work (direct competitor). If Barrister 1 has been in a big case and his opponent is Barrister 2 and both of them want to apply in the same year, neither will be motivated to give the other one a good reference as they are in competition - both to get silk and after that in their practice.
The reference forms (also on that link) are really detailed and you are supposed to provide a lot of evidence of excellence (ie. worked examples).
It isn't "This man/woman is a good chap and I thought they did a good job".
It's more "in this case, they were faced with a witness who was hysterical. They appropriately suggested the Court took a break even though it would be to their client's advantage to cross examine there and then. When Court resumed they structured their questions to get the material they needed without upsetting a very sensitive witness. I think this demonstrated excellence in appreciation of needs of the witness and working well with the court and the other parties to progress the case".
SO because filling in these forms properly is a huge amount of work, I don't think anyone is really happy to fill them in unless it is for a close buddy - but most people realise this is how the system works and are "happy" to play ball in that sense.
No you don't "owe them a favour" in any bargaining corrupt sense.
Are you QC for life once successful or can it be removed if you aren't very good later?
At the moment, it is for life. There was talk of competency re- accreditation in criminal law but that has been abandoned. You could still be disbarred of course but that is about fitness to practice rather than QC excellence.
When do people decide to hire a QC? Is it just for complex cases, or do rich people hire a QC for everything?
Usually just for diffficult cases or cases where it matters (eg. a lot at stake financially) or where the other side has a QC and there is a strategic concern that their QC will have more the ear of the Judge than your junior barrister - so "if they have one, we'll have one"
It is not unknown for the very wealthy to instruct more senior than they need but this is really against trend. It is usually the other way round. People normally want to pay as little as they can get away with so tend to instruct down. It is how you grow as a practitioner really - always doing work a bit more difficult than your level.
If need a baby junior, instruct a pupil - cheaper.
If need a senior junior, instruct a mid ranking junior
If need a QC, instruct a senior junior
If need a senior QC, instruct a baby QC
If need David Pannick QC, instruct another less expensive senior QC.
(Junior in this context just means a barrister who is not a QC - ie. a barrister who acts as a junior to a leader. It's an odd term because "a junior" strictly can apply to any one from newly qualified to 30 years experience. That is why we have the stupid term "senior junior"!)