Acknowledgements

AD gratefully acknowledges the award of a Macquarie Research Excellence Scholarship (MQRES). QAP acknowledges support from Macquarie University and the Australian Astronomical Observatory (AAO). We would like to thank the staff at the ANU Siding Spring Observatory for their support. Based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESA) and the Canadian Astronomy Data Centre (CADC/NRC/CSA). We thank the anonymous referee for helpful comments.