In the 'Missing Charts' of 1940-1952, 'White Christmas' was usually missing from the first chart of a new year, having been No. 1 on the last chart of the previous year. However, I think this may have been a deliberate exclusion.
Wiki is correct about 'That'll Be The Day'. Two other Various Artists compilations were kicked off the chart the same week (18.8.73). However, soundtracks survived (Cabaret, Clockwork Orange).
The ban seems to have been lifted in the last quarter of 1975, with several entering between 27.9.75 and 13.12.75 (source OCC archive search; 'Various Artists')