What a mess that is. Is it a working gas appliance attached to it?
Worse, in some ways! It has an oil boiler attached to it which is an old very inefficient boiler, so gases are well in excess of 300 degrees and you will notice the terminal end piece has come off. (Gases supposed to go out side vents on that flue)
That oil tank is getting some heat!
Regs on new work are oil tanks 1.8m at least from any terminal