I feel that it is not those on the left who are naïve but those on the right who seem to be under the mistaken impression that the Conservative Party has the interests of the average citizen of this country as its priority. Virtually all measures whose aims were to improve the lives of the majority population have been achieved by those on the left - with an agenda which was far to the left of anything we see now.
The Labour Party has, from its inception, been responsible for virtually all the social reforms in this country: the introduction of a state pension and the NHS, the 8-hour working day, social housing, rent controls, abolition of capital punishment, de-criminalisation of homosexuality, employment rights including maternity leave, Health & Safety at work, Employment Tribunals, legal protection for women suffering domestic abuse, access to abortion, fairer divorce laws, the Equal Pay Act, equality and anti-discrimination legislation, Open University, Sure Start centres, etc. etc. -most of which were met with opposition from the Conservatives.
I'm not quite sure therefore how those on the left who wish to maintain the improvements brought about by the Labour Party can be described as "anti-British". They may be anti many elements of the entrenched establishment which has, in the main, operated to protect their own rights and privileges - whatever the cost to the population of this or other countries - but that does not make them anti-British.