Thirsty Gull

A solitary gull has been drinking from my bird bath on a daily basis.  That's quite unusual.  My back garden isn't particularly big and it's enclosed, so herring gulls find there isn't enough runway for a good take off.  (Unless of course they spot a piece of bread from on high.  Then they all descend.)  But a few years ago a gull family did adopt the garden and I named them Mum, Dad and Junior and blipped them a few times.  I'm wondering whether this is one of the parents now on its own (herring gulls often mate for life) or even Junior, now fully grown.