Update!!
I didn't push it at all, just waited till what seemed like the right moment and this evening, she casually mentioned cycling so I casually suggested we had a go and she demurred and I asked why not and she grinned, dashed off to get changed and off we went. Everyone else in the household was out, no one would be watching, it was a very safe environment to give it a go.
I put her on my MTB - she's much taller than me so she could easily reach the ground (I know some people will say that was the wrong bike, but there we go). Firstly, we took the bike for a walk up and down our cul-de-sac so she could try braking and see how strong they were, and slowly get used to braking more gently. Then she hopped on and scooted up and down the street a few times. It became apparent that she wasn't a total beginner as she was scooting within minutes and was able to glide quite well. And then, without me even suggesting it, she started pedalling slowly and carefully! She did a few lengths of our street and we called it quits, whilst everyone was still triumphant and laughing.
So that's tonight's little moment of joy!!!