The blue-chip FTSE 100 (.FTSE) closed 0.24% up and the domestically focussed FTSE 250 (.FTMC) ended 0.15% higher.
"At the end of the day, the UK government blinked, while the BoE has seen its credibility restored," said Darby.
He added that there is room for a sizeable change in sentiment towards domestically exposed FTSE 250 which had been battered recently.
Shell (SHEL.L) is among a number of companies joining a second bidding round to acquire Danish biogas producer Nature Energy, for around $2 billion sources familiar with the matter said, as energy firms race to boost low-carbon businesses.
Bellway Plc (BWY.L) slipped 2.2% as the homebuilder warned of moderating demand, pressured by rising mortgage rates.