"try" the 2nd Monday on the month, you never know, some different extra attendees might turn up. Also, it will make a good "last meet" at the ACE Cafe before the club invasions on France.
You could try moving out of ' that-there London ' and make it a weekend event .A treasurehunt type setup or the like I vote a Midlands jolly ...........2 hrs travel max for a lot of members ,how long does it take to get north of the river these days