Quickly. Can you identify this flower?

So, this is the question.  Do you know what this flower is?

It arrived courtesy a passing bird, grew up between gardener's visits and as it was looking well established and happy I allowed it free rein.

The gardener wasn't all that happy and mumbled about creepers that went everywhere and were hard to control.

We have been rewarded with these flowers and the other day I came across another similiar creeper growing below the railway embankment, alongside the path leading from the railway station to the university.  None of its companions in that place were  rare and exotic plants.

I think it must be of the common weed variety.