The BBC's odd definition of 'cross party'

The BBC Twitter account @BBCPolitics tweeted that 'Ed Miliband shares a platform with Charles Kennedy, Baroness Williams and Green Caroline Lucas at cross party Yes'

Hmm so Labour leader shared a platform with:
1) ex-Lib Dem leader now on left of that  party
2) ex Lib Dem leader in Hose of Lords, prior to that founder of SDP and prior to that Labour MP
3) Green MP with views well to the left of mainstream politics

To the BBC that may seem 'cross party' but to me it looks more 'left of centre'. Nobody from the Conservative party, the largest party in this House of Commons. Nobody from UKIP who mostly support the Yes2AV campaign and who are gaining ground at elections to vie with LibDems for fourth place?

No to the BBC the concensus of British politics is centre left so the above four people are a cross section.