Katherine Tate's Nan character - there was a moment where she slapped someone on the back with a fixed grin on her face when it just came to me who she was reminding me of, the hair is part of it, but it is her expressions as well. Now I have seen it I keep expecting her to say 'what a beeping liberty'

https://www.youtube.com/watch?v=PayDM8DWsXY

With her helmet hair do she reminds me of Paul Michael Glaser circa 1977. I always hear the Starsky & Hutch theme in my head when I see her.