Just wanted to report a big success, the strawberry buttercream was lovely, and the cake worked out well too. A big hit. No pictures, because it was eaten in minutes, sadly. I used some of my special stock of cake flour, and it was worth it. Must get a microwave and try the flour treatment experiments.
On a related note, I wonder if senior bakers have ever regularly used the creme anglaise buttercream that Julia Childe used to use in her early cook books. That used to be my favorite - not a as complex as the mousseline.

No pictures, because it was eaten in minutes

Well, if there’s not going to be pictures, there certainly can be no better reason than that!!!!

Congratulations on a beloved cake!  Sounds like a really fabulous combo!

I was fortunate to find frozen strawberries at the local german supermarket (Lidl, for all you over there), to make the puree for the butter cream. Very inexpensive but good quality. I’ve actually manage to wean my kids off of the inevitability of chocolate.

Congratulations on what sounds like a lovely cake!  Glad you enjoyed it.