Desperate, traumatised and hungry after days locked inside Hong Kong's last besieged university, the young woman in her 20s looked down into the narrow pipes of the sewers.

The smell of effluent drifting up was not enough to put her off a last-ditch bid for freedom.

Riot police were closing in after students fortified the Hong Kong Polytechnic University campus, now a totem of pro-democracy demonstrations which have shaken the city for months.

For the woman known as K, who asked The Sunday Telegraph not to reveal her identity, there was no other choice.

Clad in the all black uniform of protesters, with a mask for good measure, she disappeared through the manhole and risked her life crawling through a fetid, cockroach-infested sewer rather than surrender.