So so annoying

SIR: Russell Davies (‘Why so?’, February issue) has completely left out of his otherwise comprehensive analysis what, to grandparents, may be the most irritating use of the word ‘so’ – as a monosyllabic response to any expression of criticism or even disagreement with the grandchild. Luckily, they seem to grow out of the habit quite soon after leaving school, but it must annoy many teachers, too. Ian Clarke, Bridgwater, Somerset.