The decrease of LTN services probably has to do with the growing attractiveness of services to LCY thanks to Euromanx and VLM. The August figures were (brackets: AUG05):
LCY 5829 (4953)
LGW 10.457 (10.778)
LTN 6691 (3432)
STN 0 (1852)
There has been an overall increase of approx. 2.000 pax on the LON market a year-to-year basis. It appears as if the capacity of the cheapish STN flights was mainly absorbed by LCY and LTN (while I would guess that the increase at LTN is mainly responsible why the LGW have taken a dive in an overall growing market). Looking at figures, it must be noted that LCY has grown despite the use of a smaller aircraft in 2006 compared to 2005 (IIRC, the number of flights has stayed the same: Three by 3W, one by VG).
Given that the market is growing, the cutback of capacity at LTN should seriously increase load factors and yields for the other companies.
As for your personal flight planning, 3W has sone reasonbly priced flights from LCY for as little as 34 GBP all incl.