We keep talking about live birth - are we sure? Here is an example of eggs not quite released.
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...live birth? - not yet but definitely female.
Of course not live birth yet.
These look like eggs.
"Egg capsules are about 1mm across and each biconvex capsule"
"...the eggs are laid in the sea in gelatinous capsules that usually contain around three eggs (although up to 9 eggs per capsule has been known). The egg capsules float in the sea and free-swimming ‘veliger’ larvae hatch after a few days" (MarLin)
I would have thought, looking at the few Web pictures, that the process was more systematic than this, rather than a random looking discharge.
I kind of hope you are right and if so it's a rare picture.
See a lookalike here, with no explanation -
A remarkable video here -
Lat/Lng: 51.3829, 1.3189
OS grid ref: TR310701