Is it safe for somebody on their own to travel in london by train late at night?

I'm a woman and there is no direct line from canary wharf to Romford - I know because I live in the docklands and my sister lives in Romford, mate it depends how streetwise you are, I am a 33 year old mixed race asian/english woman and so long as you don't look at anybody in the wrong way or go to smaller (off the main road) areas like the estates then you will be fine and I have travelled a lot later then you - anyway if it is a friday or saturday night that you travel on Romford and essex is teeming with teenage clubbers - you will be fine.