Jenny Reeves (@Jennyflyer1) was one of the first to post a picture on Twitter.
And Transport for London sounded the all-clear after the "invasion" had been averted.
The filming of Doctor Who has finished at Westminster Bridge, the Daleks are in the process of being removed.
More top news
TV veteran Sir Bruce Forsyth has died at the age of 89
Work in the tower will also pause over the bank holiday weekend.
The attacker grabbed her dog lead wrapped it round her neck and started to strangle her before running away.