While I'm here it may be worth analysing what's going on in that second pic.
The pace is being set by Martyn (leading, glasses) who is the strongest in the group. The wind is almost certainly against them and coming a bit from their left, which is why the one behind Martyn (bobble hat) has 'echeloned' to gain more shelter. The rider nearest the kerb is suffering under the pressure and is beginning to drop back, which has exposed the fourth rider to the wind (he's visibly gritting his teeth).
While I'm here it may be worth analysing what's going on in that second pic.
The pace is being set by Martyn (leading, glasses) who is the strongest in the group. The wind is almost certainly against them and coming a bit from their left, which is why the one behind Martyn (bobble hat) has 'echeloned' to gain more shelter. The rider nearest the kerb is suffering under the pressure and is beginning to drop back, which has exposed the fourth rider to the wind (he's visibly gritting his teeth).