Pharrell Williams' Happy has broken through half a million UK sales as it heads for a third week at No 1.

The track has already this week sold another 80,000 copies and by the end of business on Thursday was already 30,000 sales ahead of its nearest rival, fellow RCA-handled Timber by Pitbull featuring Kesha. That takes its cumulative tally above 500,000 units and will secure it a third non-consecutive week leading the UK singles chart this Sunday.

Williams' success ...