LONDON, Nov 5 (Reuters) - British police said on Saturday evidence showed an extreme right-wing terrorist ideology had motivated a petrol bomb attack on an immigration centre in the southern English port town of Dover on Oct. 30."There is currently nothing to suggest the offender was working alongside anyone else and there is not believed to be any wider threat to the public," a police statement said.Evidence from digital media devices suggested Leak was motivated by extreme right-wing ideology, although there were also strong indications that Leak's mental health was a factor in the attack, police said, adding that investigations are continuing."I am satisfied that the suspect's actions were primarily driven by an extremist ideology.Prime Minister Rishi Sunak has said Britain is a compassionate and welcoming place for asylum seekers, but this depends on the country being able to effectively police its borders."