It's a radiant day. Londoners have shed their winter layering to celebrate the sun. A hand through the hatch of the ice cream van is tirelessly doling out 99s. New leaves are unfurling on the horse chestnuts and my children have torn themselves from their iPods to play Piggy in the Middle in the park.
I drift into small talk with the woman who has spread her rug near ours. I've been struck by her high-spirited affection for her two small boys. We begin with the weather and graduate to jumble sales. Then she tells me how a stranger raped her in her native Zimbabwe. I notice there are knife scars on her cheek. The rape resulted in a baby. Her parents adopted it. They'd always wanted a large family. She was stricken with post-natal depression, but noone diagnosed her despair.
She fled to England to escape her past. Her parents came too, bringing the child. The child closely resembles the rapist and she found it traumatic to look at him.
Now she works as a live-in nanny mothering someone else's children. The family has just moved her from Birmingham to a Home Counties village where she knows noone and where hers is the only black skin. 'It was time,' she says resignedly. 'Time to start anew. Again!'
I want to ask her if she still sees her own child. If she dares hope for another baby or if her past has destroyed her faith in love. But her two blond charges have reclaimed her. She darts off for a game of chase. From a distance she is a carefree figure prancing over the grass in a pink designer dress she'd bought for 40p at the village fete.
The morning has shadowed a little with the trauma that she's shared. So much pain borne so smilingly. And I look afresh at the throngs basking in the spring sun and wonder about the histories hurting inside them. Then suddenly I am inspired by the thought of the courage borne invisibly beneath the mundane. And I am consoled to be reminded that for all of us, like the unfurling trees, there is always time to start anew.