They say one swallow does not a summer make. Apparently it was Aristotle who said it (thanks Wikipedia), but the point remains the same. That one brief period of happiness may just be that, rather than the indicator of more good times to come.

No doubt Morrisons CEO David Potts is acutely aware of this idiom, but nevertheless he will have been cheered by this morning’s Kantar grocery share figures that revealed how the retailer had delivered its first increase in sales since December 2013.

Morrisons sales were up just 0.1% for the 12 weeks to 24 May, but despite not being exactly stellar, they will have cheered Potts as he prepares for his first agm as CEO on Thursday.

Potts can no doubt expect an easier ride from the Bradford faithful than his predecessor Dalton Philips faced in the last couple of years. Highlights then were the savagings Philips received from the retailer’s founder Sir Ken Morrison.

It is unlikely we will witness any such fireworks this year, although there is expected to be a significant shareholder protest vote over Philips’ final payoff.

Potts has been widely lauded by Morrisons staff for the focus he has dedicated to stores during his short tenure, and clearly sales are beginning to shift in the right direction, but the key message will clearly be that there is still much hard work to come.

Delivering a short term turnaround in volumes is one thing – sustaining that momentum is quite another. And if we had to find evidence of how difficult that is right now we only have to look at Tesco. Post-Christmas, things were looking up on the sales side, while today its sales were down 1.3%.