Well, I'm not an accountant, so it's not beyond the boundaries of possibility that I'm overlooking something.
I'd like to hear what ravelston has to say.
(or London Red or one of the other professionals)
Edit: see above
It's important to differentiate between things like interest, dividends and taxes which involve cash actually flowing out of the operating entity, and the issue discount associated with financial changes or the effects of exchange rate fluctuations on the value of financial obligations or almost anything related to the PIKs, which don't involve cash leaving United.
The cash that has unambiguously left United includes around £360m of interest payments, £90m used to repurchase bonds in the couple of years before the IPO, and the £10m dividend that the Glazers paid to themselves prior to the IPO. Additionally, some of the costs associated with the various refinancings and the IPO were paid in cash (accountants, lawyers, various consultants, etc.).
The majority of the costs of the refinancings and the IPO were paid through "issue discounts" (also known as the underwriters' spread). That just means that the underwriters take a chunk of the money you raise so you have to raise a little more than you need. During the refinancings and the IPO the money raised never came near the operating entity that is United - it was simply paid to retire whatever securities were being replaced. The result is that the debt outstanding is increased by the amount of the issue discount each time it is refinanced - but this isn't a cash drain on United unless and until internally generated funds are used to pay down the debt. Hence these are potential costs that are, as yet, unrealized (and which may never be realized). On the positive side, issue discounts are amortized and thus reduce our taxable income.
There were a bunch of inter-company transfers tagged as payment for consulting and other services in the years before the IPO. There is no way of knowing the extent and value of the services provided. It's likely that at least some of those charges were genuine - it's hard to see how we could have ramped up commercial so rapidly without outside assistance. These are usually included in the estimates of the "Glazer costs" - I suspect, at least in part, erroneously.
The only impact of the PIKs on United arose from the deductability of the notional interest that was paid on them and the amortization of their issue discount. That is, their existence gave us a tax break. They were secured against the Glazers' shares so, if they had defaulted, our ownership would have passed to the lenders but there would have been no claim on United's assets.
As I said in my prior post, without the debt we would have paid approaching £300m in dividends and taxes since 2005. This should be offset against the costs associated with the debt and with the Glazers' ownership.
[Edit: I forgot the costs associated with unwinding the interest rate swap prior to the bond issue in 2010. I think we were looking at £20-£30m of cash costs.]