Figuring out gas oven temperature numbered 1 through 7 New apartment, old oven and a lot to bake with precise temperatures.
Thermostat is numbered 1 through 7 and no idea what temperatures they represent, couldn't find any identifying company logo or other signs on the oven itself or inside of it and not the owner nor any of the previous renters knew anything useful.
I have seen too many different gas mark temperature charts, none of which are scaled 1-7 and all of them are different from one another. (the one that came up the most said that 7 is 220 Celsius, but still it wasn't consistent)
I was hoping anyone here might know more than what I could find so far or even, if the gods are righteous, someone here owned/still owns that very oven and still got the manual.
Here are some pictures of the whole oven, the top part and the thermostat itself:



Lastly I'm guessing it's made in the UK since the labels are in English and the little Celsius orange light, but that's just speculations.
The mode selector dial looks more appropriate for an electric oven, but it's still (almost) certainly a &quot;Gas Mark&quot; scale.  It used to be common, though modern gas oven usually have Celsius.  I know such scales often go hotter, but 7 is high enough for almost all cooking, and I've certainly seen them stop at 7.  It's rare for electric ovens to use that scale but not unknown.
The conversion isn't usually quoted precisely, which is throwing you off.  The Wikipedia page I've linked above gives the exact conversion but rounding to the nearest 5 or better 10 °C is much more useful.opf a top
Here's a more practical table (rounded to the nearest 10°C), but gas ovens tend to be a little approximate; 1 is about 140°C and 7 about 220°C.  If you're still in doubt, you might want to get an oven thermometer, but the suggestions broadly line up with the conversions above (cakes Gas 4-6/180-200°C, roasting 5-7 or 190-220°C, meringue as low as it will go - 140°C is a bit hot really, gas 1/4 is often called for).
In fact given that you want precise temperatures and it's old, maintained for safety (at most) and not performance, an oven thermometer would be a very good idea.  This may be a cheap basic model - likely in a rented house and the lack of gas marks 8 and 9 fits with that too.  Preheating times can be quite long on some such models.