If I were Nadia Eweida, I would be starting to think that the whole world had gone completely mad. You remember Nadia, the mild-looking British Airways worker who was suspended because she wore a tiny cross round her neck for work. Everyone took her side, in 2006. The entire British press was convulsed with indignation. There were debates in the House of Commons.

The prime minister of the day, Tony Blair, weighed in with all the preachy solemnity he could muster, and advised BA to think again. Come off it, we all said: you can't stop people wearing a necklace with a cross around it. For goodness' sake - we still have a House of Commons that kicks off daily proceedings with a series of Christian prayers. We have a judicial system that invites witnesses to swear on the Bible, and the same ritual can be observed taking place in the Leveson inquiry.

The entire British landscape is a testament to Christian history, from the crosses in cemeteries to the churches that still dominate our villages. The last time I looked, British Airways still had a livery based on the Union flag - and it seemed the height of hypocrisy to indicate a socking great cross on the tailfin of every plane, but to forbid a teensy little crucifix around the neck of an employee.

Such was the general pop-eyed outcry that BA eventually caved in. After about a year of dither, it changed the rules so as to allow all members of staff to wear a discreet religious symbol. So I bet you were as stunned as I was to learn yesterday that the case was not over - and that the government appears to be backing BA's original decision.

Poor Eweida was effectively dismissed and humiliated for wearing a cross round her neck; and yet BA never accepted that its rules were discriminatory, or that she was in any way disadvantaged because of her faith.

As it happens, I met the good lady, by chance, on a crowded train in south-west London. I had a long conversation with my constituent, and I can confirm that she is neither a religious nutter nor driven by vindictiveness. She just wants the airline to accept that it was unfair and wrong, and the irony is that she has now been driven to take her case to the European Court of Human Rights in Strasbourg. And the further irony is that the British Government - a British Government whose individual members, if asked, would almost certainly agree that BA was loony in its decision - is now apparently backing that decision and opposing Eweida.

Ministers will argue, in Strasbourg, that BA was perfectly within its rights to kick her out of the workplace, because there is nothing in the ''rules'' of Christian observance that says you have to wear a cross. They will argue that wearing a cross is ''optional'', and therefore unlike wearing other items of apparel (headgear, bracelets, etc) that other religions demand of their adherents and which are therefore permissible for BA staff.

I don't know the process by which government lawyers have decided this is the right way to go, but someone needs to march into their room, grab them by the lapels, and tell them not to be such confounded idiots. They appear to be following the 2010 Court of Appeal ruling of Lord Justice Stephen Sedley, who threw out Eweida's case for discrimination and accused her of having a ''sectarian agenda''.

Sedley is a very clever man, and a distinguished jurist, but I don't think he would object if I called him the most left-wing judge of the past 50 years. You should read his judgment as a perfect example of how a brilliant mind, in the grip of strong ideological prejudice, can depart completely from common sense.

His first point, as I say, is that Christianity does not demand that its followers wear crosses - in the way that, say, Sikhism demands turbans - and that Eweida was therefore not discriminated against, and suffered no disadvantage, simply for being a Christian. Sedley makes much of this distinction between ''optional'' and ''compulsory'' bits of religious clothing or apparel, and you can see why it might be convenient for employers like BA.

Eweida might argue that her deep personal convictions drive her to wear a cross; and another female employee might argue that her deep personal convictions drive her to wear a burqa. How could BA forbid one but not the other? What if a member of cabin crew turned up insisting (as many Britons do) that she believed in the Jedi order, and that her personal convictions demanded that she dress as Princess Leia? This objection may sound logical enough; and yet it flies in the face of common sense. There is surely a world of difference between discarding a uniform, in favour of a burqa or a Princess Leia outfit, and wearing a small cross on a virtually invisible chain.

The airline was neither reasonable nor proportionate in its first response - as was shown by its subsequent capitulation - and the Appeal Court could have recognised that.

Sedley's second point is that no other Christians, in BA's entire 30,000 staff, protested in the same way, or insisted on wearing a cross, and that there was therefore no evidence that Christians were disadvantaged as a group. That may or may not be true. But if it is true that Eweida was on her own in wanting to wear a crucifix, then that surely shows she was not the thin end of the wedge, and that allowing her to wear a cross would have been a reasonable and harmless indulgence, rather than a general invitation to others to break the rules.

Eweida is a member of a group - Christians - and she wanted to express her membership of that group in a small and inoffensive way. She was suspended and sent home. She was told she could not have contact with the public. She was discriminated against. She did suffer disadvantage. It is plain as a pikestaff. Government lawyers should run up the white flag now. Never mind Strasbourg: it is time for some common sense.

London Daily Telegraph

Boris Johnson is mayor of London.