She would talk to him about it, get him to understand something of what it meant to her, and when the concerto was quite finished, she would invite him into the West Parlour to listen to it.

It was nearing completion--another week's work and what Sandy laughingly termed her "magnum opus" would be finished.

Of course Roger wouldn't be able to give her a musician's understanding of it, but he would certainly appreciate the fact that she had played it to him first of anyone.
It would go far to heal that resentful jealousy if she "shared" the concerto with him.

He would never again feel that she was keeping him outside the real interests of her life.

Probably, later on, when it was performed by a big London orchestra, under the auspices of one of the best-known conductors of the day--who happened to be a particular friend of Nan's and a staunch believer in her capacity to do good work--Roger would even begin to take a quaint kind of pride in her musical achievements.
What she purposed would involve a good deal of pluck and sacrifice.