If anyone can answer this I'd be very impressed. Before yesterday, when was the last time BBC1 averaged over 4 million between 5.15 and 6 on a normal weekday?
Pointless had 4.40m (24.8%) on Friday 23rd December 2011. Being so close to Christmas, whether that was a normal day is open to interpretation. Apart from that, you have a mix of Euro and World Cup games, possibly Wimbledon.
Neighbours had 4.01m (24.1%) officially on Thursday 19th January 2006 at 17:35.
For nostalgic purposes, the opposition that day was
How times have changed!