AIBU to not know the correct way to address an MP in a letter/email?

[JetTail]

Out of curiosity, and also to ensure that I am not automatically 'cancelled' as some sort of ignoramus (this is relevant, as I'm about to question his nonsense about claiming all great epitomes of historical lunacy are being cancelled), I'm wondering how to address someone who signs off a letter with the following: Rt Hon Jimmy Bigballs CBE MP.

Do I write:

Dear Mr. Bigballs

Or

Dear Rt Hon Mr. Bigballs?

or

Dear Rt Hon Bigballs?

or

Something else?

Yours

The soon to be Dishonoured Nelly No-balls

I really CBA to read all that. But just wanted to point out that you may have inadvertently identified yourself by including your first name in the MP's email quotation.

[quote AllOfUsAreDead]@StringFellow

Cant remember to be honest. They have a very weird job title, it essentially means secretary, but it's like 4/5 words long instead.[/quote]
Each office can have different job titles actually, some arseholes have chief of staff but others called parliamentary assistants (which aren’t the same as secretaries), then caseworkers, sometimes a separate secretary

Dear Boris ot whatever their christian name is!

@JetTail

My views are 'woke' by most standards. However, if I wish to say something, I do not want the world and its mother taking offence on behalf of someone who might be offended. If I offend you, take it up with me. If I don't offend you personally, fuck off.

That's much better

@StringFellow

Oddly none of those ring a bell, it was something else even weirder.

I email him by his first name.
Remember to include your full name and address in it though.

There is nothing honorable about my MP so I would never address him as such.

I stick to Dear Mr xxx,

There is nothing dear about him either.

Maybe I should try: Mr Tory Twunt,

I am writing to ask why you are voting to not extend free school meals to poor children during a pandemic / why you are standing behind a leader who has lied in parliament to your colleagues and the country at large and was not prepared to follow his own laws?

Yours disaffected constituent.

He replies using my firstname which rankles as I use Mr XXX