I've only read one Thirkell, Wild Strawberries, but I can immediately think of one character that certainly sounded like it might have been poking fun... the man who is obsessed with gardens, puffed up in his own consequence, has a jealous and easily bruised ego, is a mad gossipmonger, and basically mooches off various hostesses willing to put up with the way he invites himself and expects to be treated like royalty.