Just a little warning. My wife and three friends returning from London last Saturday were abandoned by AGA at Broxbourne and had to get a cab; they tried to be clever and avoid the queues hence walked up the road to near the park where a BSC driver stopped to take them back to Hertford whereupon he said their policy for when the trains weren't running was to charge individually when the trains were cancelled at the station and asked for £12 each from the four passengers. They paid unfortunately - I would have called his bluff and asked him to take me to the nearest Police station personally.
They have complained but BSC have said that because they didn't use the rank there is nothing they could do - no word on the 'policy change'. My advice would be to call a Hertford firm and meet them further up the road to avoid any possibility of this happening in the future - and to short circuit the queues!