SAPI: Output speech using the SAPI TTS engine in .NET

Today I'm posting about something which is possibly already covered elsewhere, but I'm covering it as part of a 'theme' that might appear in some of my postings, to do with making things accessible. If any of you immediately went 'ugh' and pulled a face, I hope you're not intending to work in software. Ever. Accessability isn't particularly hard and like real life, making things accessible in software requires a bit of thought and minimal time and in the case of software, probably no cost.