Paula Sherriff, MP for Dewsbury and Tracy Brabin, MP for Batley & Spen, said they were "deeply concerned" when they saw "a number of Officers and young cadets taking part in what can only be described as a Party Political broadcast" according to the MPs.
The full letter, released this morning, said: "Dear Chief Constable.
"This afternoon we, like many, were deeply concerned when we saw a number of Officers and young cadets taking part in what can only be described as a Party Political broadcast.
"In recent weeks we have spent time out with frontline staff bearing witness to the incredible hard work and bravery the police show day in day out keeping the public safe under increasing pressure. We’ve also hosted public meetings where constituents were given the chance to express their concern about the lack of visibility of Officers, slow response times and dwindling resources.
"We were therefore startled to see, when resources are so tight, a significant number of young cadets being used as set dressing for what seemed like the Prime Ministers election campaign launch.
"With this in mind, we would like to know:
"1. Were the cadets kept waiting for at least an hour in the sun?
"2. Were the Officers and cadets advised of the nature of the event. Did they provide written consent, or was there an expectation that they would agree? Were Officers given the option to decline their attendance?
"3. How much did the event cost, and what was the total expense to the taxpayer?
"4. How much notice was given to the West Yorkshire Police and Crime Commissioner and what level of detail was he provided with?
"5. Who determined/requested the Officers presence at the Prime Ministers speech?
"6. What discussions took place prior to the event, regarding the potential politicisation of West Yorkshire Police?
"We would be grateful for an early response. Please accept this communication under the auspices of the Freedom of Information Act 2000."
West Yorkshire Police have been contacted for a comment.