Resistor voltage ratings
Most folks only think that resistors have "value" and "wattage" ratings. They don't realize that they also have voltage ratings. A typical 1/4-watt carbon film resistor is rated at 250 volts while a 1/2-watt unit is rated at 300 volts. Intermittently, they'll handle 750 volts. That's why you often find lots of lower-value resistors strung together in series in higher-voltage circuits, such as for voltage dividers. In fact, Tek used half a dozen 1/2-watt 510K ohm resistors in series in the focus section of the CRT circuit for just that reason.
Of course, 270 of them in series for that intermittent rating for the 200KV is a little ridiculous! HV resistors are often made of glass or ceramics. The resistor used as the series divider for the 20KV HV probe for my VTVM was a glass thing about four inches long.
Dean