London shares tread water in early trade on Thursday as fading optimism about a Greek debt deal and an upcoming US jobs report gave investors reasons to be cautious. The blue-chip FTSE 100 index is a nudge higher, about 5 points, at at 6,614 early on, although midcaps perform less well, the FTSE 250 index drifting about 20 point to 17,694.Electricals-to-telecommunications retail titan Dixons Carph