No, I will not indulge your imagination.
Irrelevant.
First, I have read the Act. Cite to the portion of the Act that presents the criteria for "damaging" disclosure that applies to your imaginary scenario.
Second, national security is moot. Your conspiracy theory is based on the premise that the true nature of the subject vehicle is being withheld not for security purposes, but for political expediency. It is hardly possible to conceal the fire at Luton airport. There is no implication for national security in denying the cause, no potential "terrorist attack" to unravel.
Your claim is that the sitting Prime Minister has a business interest in electric vehicles and that the type of vehicle that caused the fire is being lied about to protect his interest. This does not fall even close to the Official Secrets Act.