Panmure Gordon has been looking at the life assurance sector with a generally positive eye, though it thinks the time for buying Standard Life has passed for the time being.The broker has downgraded Standard Life from 'buy' to 'hold' in the wake of the share price's significant outperformance of its peers over the past 12 months. The share price gain was driven, in Panmure's view, by the strength of the company's balance sheet in comparison with its peers 'but we think such outperformance is unlikely to continue in rising investment markets,' the broker said.On the sector as a whole, Panmure notes that it has rallied sharply since its recent low point in March but believes there are more gains to come as it bounces back from the share price losses suffered last year. 'The announced delay of the mandatory introduction of MCEV until 2011 removes a black cloud hanging over the sector. We have increased our target prices on the large-cap UK life insurers and our preferred plays are Prudential and Aviva,' the broker said.