The London plane is a hybrid of an Oriental plane and an American plane, is deciduous, and grows up to 20–35 m tall, with trunks of up to 3m in circumference. They are common in other cities, such as Paris, where readers will be unsurprised to hear they are not referred to as London Planes.
Characteristically, they can be spotted by their pairs of round spiky nuts, and their flaky pale grey-green bark, which flakes away and helps the tree cope with all the pollution.
If they could just get the bits which get in your author's eyes sorted, they'd be perfect, and that is only really a problem on windy days. For more on the London Plane, see the fantastic Trees of London website at http://www.londontrees.co.uk/london-plane.html