By Shanima A and Sinchita Mitra (Reuters) -Britain on Thursday moved forward on approving the acquisition of London-listed defence firm Ultra Electronics by rival Cobham, owned by U.S. private equity firm Advent, after having raised security concerns over the planned transaction. The UK government has started a consultation process over the 2.57-billion-pound ($3.14 billion) deal, following advice from the Ministry of Defence, and said the Business Secretary “is minded to accept undertakings offered by Cobham” to address the concerns. “Today’s announcement is a positive step for investment in …