It's amazing to see how leftists suddenly love the police
Hate to burst your bubble, but leftists don't have problems with police as a whole. Leftists have problems with police who don't do their job correctly or fairly, and I'm pretty sure May didn't cut police because of those aforementioned reasons.
It depends on the leftist. Some on the radical left, namely anarchists, view the police as a tool of the capitalist class to control the lower classes, and a relatively cheap mechanism to protect their private property.