I suspect that this was to do with landing distance. From memory I think that the landing distance available (LDA) for Southends runway 06 is around 100 metres or so shorter than 24. For some biz jets that will give a problem for public transport operations and they will need a fair headwind to get in legally. This problem is compounded by some aircraft now having a different landing distance requirement (LDR) depending on the glideslope angle with angles of 3.4 degrees or less requiring more runway than 3.5 degrees or more. 06 PAPIs are only set at 3.0deg whereas 24 ILS is 3.5 deg. Hope this helps.
Although not relevant to Southend, aircraft that are certified for steep approaches e.g. London City, which is 5.5 degrees, have yet another set of landing tables in which the LDR is shorter still.