He noted that the euphemisms Wong used to communicate with accomplices indicated they had been galvanised by the 2019 social unrest into committing the “despicable” and “cowardly” crime.

“Whatever the reason for delivering the raw materials, the defendant’s offence was no different from one of conspiracy to produce explosives. He was not simply an errand boy as the defence suggested,” Kwok said in sentencing.

In a previous hearing, Kwok stressed he would not increase Wong’s sentence on the grounds of his hostility towards authorities or sympathy shown to the 2019 protests triggered by the now-withdrawn extradition bill.

But Kwok said on Monday that “terrorists who resented the government and police” deserved hefty sentences.

He also referred to mitigation letters written by Wong’s schoolteachers, who believed the engineer landed himself in court under the misguided notion he could achieve justice by transgressing the law. “This way of thinking is absolutely twisted,” the judge warned.

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The engineer was intercepted outside Wing Fok Centre in Fanling on the afternoon of February 8 that year after leaving a high-rise flat in the building with a silver suitcase.

Inside the suitcase police found nine packs of powder weighing more than 23.2kg, as well as 1.26kg of sparklers, 127 grams of firecrackers and three sets of wireless controllers, two of which were functional.

Government chemists identified the powders as potassium nitrate, iron oxide, magnesium, aluminium and sulphur, which could be used to produce flash powders and thermites.

Flash powders and thermites are pyrotechnic compositions, the former burns quickly and produces loud noises, while the latter creates brief bursts of heat.

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The force also seized a nylon bag containing a gas mask, a pair of arm protectors, a box of gloves and 285 gas filters.

Conversation records on messaging app Telegram showed Wong had agreed to deliver the luggage and bag to a man who said he was about to “make cakes”.

Wong, using the alias Kevin Chan, said the suitcase contained raw chemicals and described the protective gear inside the bag as “stationery”.

In mitigation, defence lawyers highlighted Wong’s Christian faith and regular donations made to poor families in Southeast Asian and African countries as evidence of his good character.

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They said the explosives seized in the present case posed no imminent danger to society as they were semi-finished products.

But the judge noted the defendant was just one step away from completing the improvised bombs, adding his personal circumstances were not effective mitigating factors in sentencing for a “very serious” offence.

He started the sentence at six years’ imprisonment before trimming the term to 40 months on the grounds of Wong’s guilty plea and the unfinished state of the explosives.

Possessing explosive substances is punishable by up to 14 years’ imprisonment, but capped at seven years at the District Court.

Wong’s co-defendant, 64-year-old decoration worker Cheung Yuk-kau, has denied charges stemming from a variety of weapons police seized from the Fanling flat. He will stand trial at the District Court in August.