The proof is in their response to their 2019/20 annual review questionnaire, specifically question 112 (p 70) in which they say:
Police is currently developing a 10-Year Fleet Strategy (2020-30), which will include a roadmap to reducing C02 emissions and improving sustainability across the Police Fleet over the next decade.According to the document properties, this document was compiled on 23 February, shortly before their annual review hearings began. At this stage, according to the Ombudsman's final opinion, the police had "realised... that there was no 10-year plan", and had extended (and were about to refuse) the request "to buy more time to try and get its internal organisational reality to match its public statement". But I guess no-one passed that on to the poor schmucks preparing for the annual review, because the lie made it in anyway.
"Deliberately attempting to mislead the House or a committee (by way of statement, evidence, or petition)" is a textbook example of contempt. There's an obvious question here about whether the lie was deliberate, and the select committee should look into it. But the charitable answer suggests an organisation so incompetent and dysfunctional that one part doesn't know what the other is doing, and where people at the top lie to the public and everyone just obediently repeats it and tries to bury any evidence to the contrary. And that seems like something the select committee might want to look into as well.