Two situations in which elections and voting are mentioned in Girl, 20:

p. 146

[...] I picked up the Sunday Times magazine section and started reading about poverty and oppression in British Honduras. Vivienne was reading on with equal attention, for after a few moments she said,

'Doug, what's a ...? I can't even pronounce it. Something about...'

I dropped Honduras and went over to her. My more direct route being blocked by her breakfast tray and the chair it rested on, I made my approach via my side of the bed. Our shoulders touched.

'Where?'

'Here.'

She was holding the paper in a rather awkward position, low down and close to her, so that I had to lean some way across to get a view of the paragraph she was pointing to. As I did so, I noticed at close range, but in adequate focus, that the front of the bed-jacket had fallen apart and that a nipple was protruding from inside the Norma-style nightdress.

'A psephologist is a man who knows about elections,' I said, stumbling a little over the last word and taking off my glasses.

'Oh, darling...'

The remainder of the day passed pleasantly enough. [...]

p. 148

[...] Come the first week of September she can vote - not a right I can see her exercising much, admittedly - and she can marry who she likes,' he said, pouring me more champagne with a casual and yet intent air. [...]