When its night in England its also night over almost half the planet. When Mars is visible from England its also visible from almost half the planet. Because Mars is not necessarily in direct opposition to the sun, these halves are not the same exactly. But in principle up to half of all of the rockets launched would be expected to be visible from England.

Except for the English weather. Astronomers know that its very often cloudy in England. Very very often. Which is why the modern day equivalents of Ogilvie put their telescopes in foreign countries. Does anybody who has read the book recently know whether Ogilvie complains about the weather? He would not be much of an astronomer if he did not.

So yes there could be many more rockets. But Ogilvie would be spitting feathers about not being able to see them because it was cloudy.

Wells of course studied biology, but at what is now Imperial College. So he would have been aware of all of this.