AOG
You asked:
[i]"So it is perfectly in order and within the law for you to criticise a person's brain power, but exactly opposite for anyone if they chose to criticise you for your skin colour."[i]
There is no law against criticising someone based on their race.
It's against the law to refuse goods and services to anyone based on a number of criteria (including age, by the way)
Political allegiances are not covered by the Eqaulities Act.
Neither are football allegiences or membership of WI.
You can lawfully refuse a job to someone based on them being a member of a political party, but not because they are Christian, Jewish, a woman, disabled, gay, straight, able-bodied.