Cooker connection ...

as far as I am aware flexi hoses are still commonly used for free-standing cooker. Its built in hobs that need rigid piping. Make sure your fitter fits the anti tilt device on the cooker as well.

Or a chain: an anti-tilt bracket on a range is particularly ridiculous since you'd have to be built like a sumo wrestler to tilt it over whereas there's still a danger of straining the hose by moving the cooker to get access behind it.

Good point. Now I come to think back, the flexi-hose installation that I had some years back, had a chain on a hook in the wall.

Arfa

Well there are two functions. The cooker requires [may need] an anti tilt so that leaning on the oven door doesn't tip pans of boiling stuff over the front edge. The chain ensures that, when the cooker is pulled out to clean behind (or whatever) no strain is taken by the hose as the chain tightens first. I think a gas installer would only worry about the second as it's part of the gas safety.

And with lightweight modern cookers with big heavy glass oven doors you don't need to put much weight on the door to tip it either. Just resting the weight of your arm on it can do it. BTDTGTTS, fortunately whilst installing.

Second being the safety chain first anti tilt device. Any "competent" installer would fit and test both. See other thread "CORGI engineer required to install new radiator?"

The chain or anti-tilt device is to protect the hose, not the user from spilling pans of chip fat. (Otherwise we'd have the same regs for electric cookers.)

I have electric ones with the same anti tilt mechanisms...

Indeed, and how does the anti tilt device protect the hose if you pull it forward.? The only reliable way is to have a chain next to the hose but shorter than it!

Regs aside, I can see real practical and worthwhile reasons for having anti-tilt - but less so for protection of the hose. ISTM that the danger from tipping some free standing cookers is quite significant - especially those with bottom hinged oven doors. I would expect many people never bother to pull the cooker out however.