This email really is about a footnote in Vol. 3 and not about the House of Lords!
Apologies for mistaking 1926 and 1927 in my Footnote message. Although the footnotes jump between the years, it was a careless mistake because the General Strike of 1926 is the backdrop for the events and partially explains why Osbert Sitwell could not immediately reply to V's letter.
Thank you for the reference to Russell's letters which, in part, corroborates S-Y's account.
It looks to me that the confusing footnotes are deliberately meant to obscure the incident. Reviewers have praised the "comprehensive" footnotes, but I find them often verbose, and sometimes they stray into commentary rather than elucidation.
Here is a longer excerpt from Painted Shadow (already referred to by Rick) about V and Mr. Haden Guest:
By 13 March Ottoline had learnt the identity of Vivien's supposed lover. She noted in her journal that Vivien was in love with a Mr. Haden Guest, or was using his "ardent attentions" to provoke Tom. Haden Guest was probably one of the young officers Ottoline has entertained at Garsington after the war . . . .The relationship between Vivien and Haden Guest no doubt ripened during the period of Tom's absence in Cambridge from 26 January 1926 . . . .