Scouring powder

I use a dishwasher tablet,works really well.
Put it on the bottom of the oven,add a ittle water ,turn the oven on and leave it on for approx 5 minutes and rub in then wipe off.

Amazon sell Vim.

Be careful with Bar Keepers friend, it will damage your nails. I always wear my Marigolds these days as some cleaners are very abrasive.

I remember Vim and Ajax. In time our cast iron bath had the enamel surface scoured away by my mum’s diligent cleaning.

There are chemical alternatives for ovens. They spray or wipe on, reduce the burnt on bits to a sludge then wipe off, thereby preserving the surface.

I think you will find that The Pink Stuff is the new Vim. Less than a pound in most B and M stores

Some of them had minute particles in them which damage wildlife and oceans.

They just started producing things like Cif that maybe were not as abrasive as Vim and wouldn't damage the new finishes and coatings on new ovens , sinks etc.
I'm sure I have seen Vim in Asda at some point fairly recently

try barkeepers friend from amazon