Harris was handed a huge slice of luck midway through the first half as home goalkeeper James Belshaw passed the ball straight to him.
Demonstrators, many wearing keffiyehs, and some with Palestine flags, started gathering on the Embankment at midday.
The attack came after police on Saturday said they detained 76 people and checked nearly 50,000 schools following two attacks earlier in the week.
Humidity defied an absence of over a year to lead home an Andrew Balding one-two-three from The Lost King and High Stock in the Group Three Modern Games Darley Stakes at Newmarket.
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