The failed asylum seekers included 14 Tamils, 9 Sinhalese and 5 Muslims.
A special charter flight landed at the Colombo international airport this morning accompanied by UK Border Agency officials, airport officials said.
A similar group of 23 deportees had arrived on September 20.
Officials said the total number of the group was to be over 60. But last minute legal proceedings on behalf of the deportees had prevented several of them from being sent back.
Sri Lanka has denied claims of New York-based Human Rights Watch that previous returnees had been harassed.
However, the returnees are quizzed by the police at the airport.
The failed asylum seekers are sent back because the situation in Sri Lanka has improved much since the end of the military campaign against the LTTE, British authorities maintain.
Tens of thousands of Tamils fled Sri Lanka after the outbreak of communal violence in July 1983.
They now constitute the formidable Tamil diaspora and are a key to achieving a lasting solution to the ethnic impasse in the island.
The country is dominated by the Sinhala Buddhist majority.