Foods & cuts · King prawn
King prawns in the shell
Prawns grilled in their shells, which insulate the flesh and hold moisture in. The FSA's cue is firm and opaque flesh rather than a temperature.
What it is
- Form
- In the shell
- Typical weight
- 20–35 g
- Typical thickness
- 20–30 mm
- Cut
- Not a cut of anything
Why it behaves as it does
The shell is the variable, not the size. It insulates, so a shell-on prawn takes longer and forgives more; it also holds moisture against the flesh, which is why shell-on prawns are so much harder to dry out than peeled ones. BBQHQ keeps shell-on and peeled as separate foods for that reason and carries no shared duration between them.
When is it done?
Food-safety endpoint
Food Standards Agency
In the UK, prawns, scallops, crab and lobster are cooked when the flesh has become firm and opaque.
The rule and its source
In the UK, prawns, scallops, crab and lobster are cooked when the flesh has become firm and opaque.
Well established
Food Standards Agency — States this directly
“prawns, scallops, crab, and lobster flesh should become firm and opaque”
- How it was measured:
- A cue, not a temperature. No figure is given for any of the four.
- Where it applies:
- England, Wales and Northern Ireland.
About this source · Original · retrieved 2026-08-16
When it goes wrong
- It came out tough
- Prawns, scallops, squid, lobster or octopus came out rubbery — 3 distinguishable causes.
Afterwards
Cooling, keeping and reheating what is left is general guidance for barbecue leftovers. Neither UK authority publishes anything specific to king prawns in the shell, and BBQHQ does not invent a distinction they do not make.