Airwave (the company that runs the network) have issued a statement to say that the radio system worked fine and that they have records to prove it!
I imagine there was a bit of confusion with regards to who should be on what talk group etc. and probably a bit of channel queueing.
In a closed network, who can say? It's the literally the word of the cops on the street versus the executives in the office and whatever documentation they present (remember, if they make the documentation, so they can select what they show and what they don't). I'm leary of this sort of situation from the UK, as the boardroom Brits tend to state their case in (to my view) a bombastic and callous way.
I'm not sure who to believe, actually, because I see some of the spectacle of tabloid "journalism" (read: stirring the pot to incite people into buying the Mirror) in the article, too.
We'll be like this in 10 years if we continue to cruise down the road where a network maintained by a third party can provide 100% of the telecommunications and data services. Without an ombudsman and strong preferential bias toward field personnel - and their direct involvement in strong stakeholder and shareholder groups, I expect we'll be seeing media spin and backpedaling in response to newly identified network deficiencies rather than investments in capacity, network integrity, and survivability. If you are a cop, firefighter, EMT, or other public employee reading this, insist that you stay engaged in and informed about your communications systems - most especially if "D Block" takes off and is operated by some monolithic company hundreds of miles away from you.