induction hob on a 13A spur

[mdbalson]

Yes that is what pyro is, it is cable which is made by placing copper rods inside a circular copper tube and filling the intervening spaces with dry magnesium oxide powder, which acts as an insulator. Pyro is a fire resistant cable, it can also be covered with a plastic sheath which also provides additional corrosion protection for the copper sheath.

Click here for a picture of what the inside of pyro looks like

 

[Taylortwocities]

no idea what it feeds.?

You need to remove each fuse one at a time and see what does what.

it is not bare wire as far as i can tell...

it appears to be wire enclosed in a steel tubing.?

Its a special type of wire known as 'PYRO'. Used for surface & fire alarm wiring but also it used to be used to run power to outbuildings/garages etc.

there is a cooker isolator, two power showers, a burgular alarm, as well as the usual lights and sockets.....?

You already have a substantial load. You should have someone evaluate your expected maximum demand and look at the rating of the supply. Two power showers + a cooker + your induction hob could blow the budget.

could i double up on the upstairs and downstairs lighting on one fuse ?

It depends on what is on the circuits and the loads. Again it needs a survey before doing this.