Mr Mawdsley, a 26-year-old Bristol University graduate, was sentenced earlier this month for illegally entering Burma and carrying anti-government literature. It was the third time in two years he had entered the country to protest against the denial of human rights.
Diana Mawdsley said she had accepted the possibility that she might not get to see her son until he was 43, but was hoping to be allowed to visit him. "Every day I have faxed the embassy to ask for a visit. I haven't protested against the length of the sentence but not one [fax] has been acknowledged," she told John Peel on BBC Radio 4's Home Truths programme.
Mrs Mawdsley said her son had been visited by the British vice-consul and was in good health, but that he had been threatened with torture if he failed to recognise the legitimacy of the junta, "and he will never do that".
"He wants to speak to the guards and to the prisoners, that is why they are keeping him in solitary," she said. "If he were to die in prison I would mourn my son but I wouldn't feel resentment."
Last year, following protests by the British embassy in Rangoon, Mr Mawdsley was released after 99 days of a five-year prison sentence for illegal entry into Burma. He was warned by the Burmese authorities that he would be dealt with severely if he returned.
His family knew he was going back to distribute anti-government literature inside Burma, and although they would have preferred him to do so outside the country, they respected his decision. Even though his action had been quite deliberate, Mrs Mawdsley said, the family had been devastated by the severity of his sentence.
"He knew would be arrested, but his point was that, as a young white English man, he would have us fighting for him and the Foreign Office would know where he was, whereas the Burmese who have been arrested have no voice to speak for them and nobody knows where they are. I admire the stand that he has taken and his courage." She herself had experienced the results of what he was fighting against when she worked in a clinic near the Thai border and saw "men without feet and legs and malnourished babies".
Last week, the Foreign Office said that senior figures in the Burmese military regime were seriously considering concerns raised about Mr Mawdsley and 28-year-old Rachel Goldwyn from London, who was jailed for seven years for staging a pro-democracy protest earlier this month.
The statement followed a request by the British ambassador to Rangoon, John Jenkins, for access to both prisoners and for Ms Goldwyn's appeal to be speeded up.
Mr Mawdsley had taught in a school he set up deep in the jungle in Shan state on the Thai border where, since 1996, the Burmese military has destroyed more than 1,400 villages and uprooted 300,000 people. The school was destroyed in one of the attacks.
Burma's military regime, which has been in power since 1962, has frequently been condemned for its abuses of human rights and suppression of the pro-democracy movement.