Run Code On UI Thread in Renderer For Android

I have some code in a renderer for an Android implementation of a custom control to be used in Forms

I have a Task, and in the ContinueWith method (which will be on a non-UI thread) I want to run some control-updating code on the UI thread.

I've seen Activity.RunOnUIThread, but I cant seem to find a reference to the current activity from my renderer to achieve this.

I'm obviously missing something very obvious, can anyone help me work this out

Thanks

Dean