In 2011, former UK Prime Minister David Cameron, during a speech on immigration, warned of a ''discomfort and disjointedness'' in communities with large immigrant populations.
Prime Minister Theresa May has also, on many occasions, expressed her concerns about the loss of social cohesion and a dilution of "British values".
There are many white Britons who feel the doctrine of multiculturalism has left them with a toxic legacy, creating a divided Britain without a sense of common identity.
Anyone who has lived in the UK for a considerable time, as I have, would agree there are many ethnic communities who live quite separate lives without ever fully assimilating into their host communities. But is that really a problem?
Research conducted by Alan Manning has found that separation between communities does not lead to feeling of alienation among migrant groups.
According to Manning, the biggest problem with multiculturalism is its failure to sustain support among parts of the white British population, who are sceptical about the compatibility of their identity with the identity of the ethnic or religious minority groups.
Another major problem is the perception of a conflict with ethnic minorities over resources such as social housing.
These tensions would not exist if the host population felt secure about its future prospects and did not suffer from neglect.
A good example of how conflict of interest between two stressed groups can become a source of tension, is the arrival of Uber in the taxi market.
In a recent trip to London, the hateful way some London taxi drivers talked about Uber drivers truly stunned me. It was obvious they resented Uber drivers not because they were murderers and rapists as they called them, but because they were seen as an economic threat.
The effect of large-scale migration on an ill-prepared country could stir up similar levels of resentment among the host nation and no amount of migrant assimilation would ever change that.
The problem with multiculturalism is the lack of support for the host nation, not lack of integration.
In 1966 the then-British Home Secretary, Roy Jenkins, said: "I do not regard [integration] as meaning the loss, by immigrants, of their own national characteristics and culture. I do not think that we need in this country a 'melting pot', which will turn everybody out in a common mould, as one of a series of carbon copies of someone's misplaced vision of the stereotyped Englishman ... I define integration, therefore, not as a flattening process of assimilation but as equal opportunity, accompanied by cultural diversity, in an atmosphere of mutual tolerance."
A harmonious society is one where everyone has a cultural anchor and feels a sense of belonging. The best way of making minorities feel at home is by allowing them to retain their culture and by eliminating discrimination against them.
Immigrants are equal beneficiaries of a well-functioning society and will reciprocate the respect shown to their culture by embracing the identity of their host country and by adopting the values needed for social cohesion and harmony.
Last June, another 52-year-old terrorist, white supremacist Thomas Mair, murdered the British MP Jo Cox. As horrendous and barbaric as these acts of terrorism are, they thankfully remain few and far between. But, clearly, all is not well in Britain.
There has been an explosion of mental health problems in the UK and the biggest killer of men aged between 29 and 49 is suicide.
If Britain is really serious about the wellbeing of its citizens, it needs to look beyond blaming multiculturalism and take a closer look at its economical and social policies that have left so many behind.
• Donna Miles-Mojab is a British-born Iranian living in New Zealand.
