Did I see something illegal?

On my way home, I saw a cyclist slowed down and peered at the glass of a park lorry.  I thought he was trying to be a peeping tom but later I realised that he was looking *through* the glass.
There's about 6 men near a parked van.  A tall lady who looked china born was on the floor.  She sounded like she was sobbing.  4 of them lifted her off the road and carried her into the van, closed the door and boarded.
Just like that.
This did not escape the attentions of the patrons of the nearby coffeeshop who were all trying to watch discreetly.  So it looked like an abduction to everyone but no one wanted to get into trouble.  I took a look at the plate - PA 2248 (?)
Is that a local car plate?