I am speaking of my last 15 years in London working in derivatives/front office IT, and interviewing for many jobs in front office IT. It is very exceptional to find banks that will organise IT to report into the front office structure - this doesn't occur, and I almost never hear of such a thing when I see job specs.
It's not all of IT, but it's not unusual for quant dev type roles to report to the front-office (either singly or as part of a dual-reporting structure). The reporting doesn't have to be direct for dev bonuses to be tied to PnL either, what I've seen happen at some places is that a certain percentage of the desk bonus pool is assigned to the development team and the development team management than decide how to split that pool among the developers.
Go to efinancialcareers and search for "PnL bonus" if you want to see some examples of job specs mentioning it.
