I used to travel around the underground system lots with a buggy or pram...first a bugaboo, then a mclaren. I rarely found myself with no offers of help, but be clear about where you want your helper to hold the buggy, rather than Wobbling to the top...people will always be patient.
With escalators ALWAYS be above the buggy, so go forwards onto down escalators, and reverse Pulling the buggy behind you when going up. This means you are always in control...if you go up an escalator trying to hold the buggy in front of you, and it gets stuck, then you cant see the problem to rectify it.
Take your time to position the wheels before you step on so you are a couple of inches away from the side of the escalator when you pull or push the buggy on. Lean the buggy so the weight is just on the back two wheels and step on so that you are one or two steps above the buggy wheels. When the steps start to raise r behind the back wheel then pull the buggy towards you so that it stops up against the step, and hold it there with one hand and hold the rail with the other hand.
You will be in complete control of the buggy, to either just walk straight forward To get off if you are going down, or to pull it off backwards if going up.
London underground escalators tend to have a longer flat section stepping on and off than lots of shops do, so more time to do it. Also, dont be scared to ask someone to stand on the step in front just in case...even as a confident traveller, i would often find the person in front would automatically hold onto the buggy to help, and i do it myself now, especially if the person looks anxious!
If you are coming off an up escalator, dont be too quick to turn around...make sure you are well clear of people coming up behind you before you turn the buggy around, so you dont block them.
This might sound a bit complicated, but it isnt...just stay above buggy, 2 inches from side, and brace wheel against the step on two wheels.