references

[Lightsareonnobodyshome]

I am in the process of applying for a new role, the line manager is someone I have worked with previously, is it a conflict of interest to out her as one of my referee's ...?

The fact that the line manager already knows you is a big advantage, assuming you got on well with her previously. But if I were you I'd give her a heads up before putting her down as a referee not only to highlight the fact that you're applying but also to check she would support you. Good luck!