Does anyone know what this bird is and where it might be going?

Here’s a question for any keen birders among you.

We think this is an egret, possibly a juvenile? It was photographed resting on one of the yachts taking part in the ARC in early December, at that time west of Cape Verde and about 1,000 miles off the African coast.

It flew off but the following day a similar white bird was reported on a boat 25 miles further west.

I’m just writing about it for our follow-up report on the ARC and wondering if, as the photographer Clare Pengelly and I reckon, it is indeed an egret; if anyone knows what type it is; and if, as I think, it was an ill-fated vagrant blown horribly off course?

As far as I know, egrets only make shortish migrations, they wouldn’t be going across the Atlantic, would they?