Myself as well, arrived at exactly 20.00 on the 16th to hear the allocution, as it turns out we could have returned at any time since then, like you I didn't expect it to be the case and had to decide instantly, financially things would have been far better had I remained in the UK and I would have relet the house that I had until then intended to sell.
My decision was made on an assessment of the risk, I decided, rightly as has been proved that a confimement in France would be more strict, better observed, over quicker and ultimately a much safer place to be and to hell with the cost.