English Part-Time nanny (Cologne)

Hi,
We will return from our expat assignment in London in July this year.
During these 2 years our two boys grew up bilingual. By the time of our return they will be 5 and nearly 4 years old.
Now we are looking for a part-time nanny / experienced babysitter who can look after them for about 20h/week starting in August this year. The boys will start a bilingual nursery in November too. We would like he/she to speak English to them only, so native speaker would be perfect. No need of German skills but a drivers licence would be a big plus too.

Anybody out there who knows somebody?