@rich-nguyen is right ...

```
curl -i 'http://www.theguardian.com/preference/platform/mobile?page=http%3A%2F%2Fwww.theguardian.com%2Fuk%3Fview%3Dmobile%23foo'
```

Gives me a `Location:` with the #foo at the end, which browsers will obey.

@mattosborn needs to make sure that [prefs URL](https://gist.github.com/mattosborn/2a7643927910ca7aea54#file-gistfile1-html-L98) is encoded though.