OK, you want some personal facts for holding into LHR - extracted from my logbooks since 1994 (when I first started recording holding times)!
Forgive the formatting, but the columns are Year; #Approaches; Total Holding (mins); Max Hold; Ave hold (mins)
1994 133 689 34 5.18
1995 57 239 29 4.19
1997 19 41 15 2.16
1998 26 83 20 3.19
1999 25 42 12 0.59
2000 24 71 10 2.96
2001 71 387 39 5.45
2002 173 897 27 5.19
2003 189 1176 40 6.22
2004 186 952 26 5.12
2005 165 733 40 4.44
2006 46 141 16 3.06
2007 43 145 15 3.37
2008 45 193 21 4.29
2009 32 107 17 3.34
1994-5 = shorthaul
1997-part 2001 = longhaul
part 2001-2005 = shorthaul
2006-2009 = longhaul
Other places where holds are not uncommon are LGW, ZRH, FRA, BCN, MAN, JFK, SFO, DEL, BOM.