I meant to ask this question in December. The first Messiah performance I saw in London was at Royal Albert Hall in 1961. Everyone stood for the Hallelujah Chorus, as they have at every other of the dozens of Messiah performances I have attended, both in the US and UK (including St Martin-in-the-Fields in London). So I was surprised this past Christmas when I attended an excellent performance at the Barbican and perhaps 20 to 25% of the audience did not stand for the Chorus. Is this ignorance of historical custom, or intentional flouting of something they consider old-fashioned?