‘There’ll be bluebirds over/ The white cliffs of Dover/ Tomorrow/ Just you wait and see.’

So runs the first verse of Dame Vera Lynn’s iconic wartime song The White Cliffs of Dover.

Our blue birds, swallows,may not grace the skies as early as tomorrow but they should fly in over the next few days.

Having spent our winter sunning themselves in extensive reed beds and wetland areas near Cape Town, swallows begin to leave South Africa in mid-February to undertake their epic 6,000-mile journey to Britain. Weather permitting, they travel in loose flocks at the rate of about 200 miles each day, roosting at night in long grass.

On the way, swallows fly over 14 countries beginning at Namibia and taking in Zambia, the Congo states, Cameroon, Nigeria, Algeria, Morocco, Gibraltar, Spain and France, before finally reaching the south coast of England in April.

What an incredible flight: across the Sahara, forests, mountains and grassy plains, at the mercy of predators, vagaries of weather and head winds, which limit feeding opportunities.

Males, in pristine new plumage arrive about a week before females to set up new or reclaim last year’s territories. I look forward to welcoming the birds back to their nesting sites along the riverside at Kingston.