Forget Hilary Barry's Formal Friday, the McCaws seem to have taken lockdown dressing-up to a whole new level.

Or perhaps it's just that the boredom of restrictions really got to them before Level 2 kicked in.

But it turns out Richie and Gemma McCaw have taken up knitting to help keep the babies of the South Island warm, and are calling for others to do the same.

Last night Gemma - a former Black Sticks hockey player - posted on Instagram a photo of her and husband Richie - a former All Blacks captain - knitting small hats to donate to Dunedin Hospital's Queen Mary Maternity Ward and to Christchurch Women's Hospital.

The pair had never knitted before, but decided to give it a go.

"We thought we should step outside our comfort zone so we've decided to each knit a woollen hat," she said, and encouraged others to take up their knitting needles and do the same.

The Southern District Health Board put out a call for knitted beanies last month for Queen Mary and had received many donations.

Earlier this week an SDHB spokeswoman said the response had been "overwhelming" and if avid knitters were keen for more projects, it was also short of knitted "Twiddle Muffs".

Twiddle Muffs are knitted muffs with items attached to help keep patients' hands active and busy.

They are especially good for people with dementia or delirium, who often have restless hands, and they provide a great source of visual, tactile, and sensory stimulation while keeping hands snug and warm.