Speaking on his
Price of Football Podcast, leading football finance expert Kieran Maguire explained: "In terms of individual deals, let's say people believe you have a budget of £50m this summer and you go and sign a player for £40m, selling clubs know that you've not got a lot of money left.
"So by keeping the fees undisclosed, you create a bit of uncertainty. I know practically all of Brighton's deals when we buy players are for undisclosed fees. We are owned by a poker player, and he will say, 'never reveal anything of your hand'. And that's why we see so many individual deals for undisclosed fees.
"Nobody is entitled to know what you and I earn because that is private information. In the same way, these are private limited companies and therefore they can argue that in terms of individual transactions, 'we're not going to give anything away'.
"It's the same as individual wage packages, they don't give anything away. Where there is a statutory obligation, for example, to disclose the total amount of money paid in wages, that's when the club will show it. Similarly, clubs are obliged to show the total amount paid for transfer fees in a financial year in their yearly accounts.
"It's simply a case that there is no legal obligation to show things on a forensic or granular level in terms of individual purchases or sales. Sometimes they might choose to do it. That can often be in an attempt to send out a message, maybe to the fanbase - like, 'look at us, we've just spent X amount of millions on this player'. But most of the time they would rather keep it closer to their chest."
In the same way, as Maguire explains it above for the buying club, it works for the selling club too. If Boro were to sell somebody this summer that would need replacing, it wouldn't be advantageous to them for it to be public knowledge how much they'd just received in selling a player.
If the selling club of the player Boro were looking at as a replacement were aware of a significant transfer fee just received by Boro then there would be nothing stopping them adding a little extra money to their valuation of the player in question, making negotiations more complicated.