A former senior manager at the British Council who was sacked over anti-monarchy comments on a Facebook post that described Prince George as “a f***ing d***head” has lost her employment tribunal claim for wrongful dismissal and discrimination.

Angela Gibbins was dismissed from her £77,800-a-year job as head of global estates at the British Council on 8 August 2016, after comments she had made on Facebook criticising the monarchy and Prince George appeared in The Sun newspaper, causing a backlash against her and the charity.

The Queen is the patron of the British Council, which had an income of £979.6m in the year to 31 March 2016.

An image of Prince George was posted by the band the Dub Pistols on its Facebook page, with the caption “I know he’s only 2 years old, but Prince George already looks like a f***ing d***head”. The band added: “Too much?”

In a discussion with friends underneath the picture, which Gibbins said she believed was visible only to her 150 Facebook friends, Gibbins commented: “White privilege. That cheeky grin is the (already locked-in) innate knowledge that he is royal, rich, advantaged and will never know *any* difficulties or hardships in life. Let’s find photos of 3yo Syrian refugee children and see if they look alike, eh?”

She went on to say she did not hate any human being, but added: “I don’t believe the royal family have any place in a modern democracy, least of all when they live on public money.”

Tribunal papers published last week say it was unclear how the comments came into the public domain, but they might have been passed on by one of Gibbins’ friends or been visible to friends of friends.

The Sun’s initial coverage of the comments failed to make clear that Gibbins herself was not responsible for the obscene remark about Prince George in the picture’s caption, and provoked outrage against the charity and calls for Gibbins to be sacked.

An internal British Council investigation into the incident concluded that Gibbins had, although inadvertently, breached the council’s code of conduct in making the comments and brought the charity into disrepute, according to the tribunal papers.

Gibbins took the charity to tribunal, arguing that she had been discriminated against because of her republican beliefs and had been unfairly or wrongfully dismissed.

But the tribunal, which heard the case in July, rejected her claims, concluding there had been “reckless risk-taking” and “gross misconduct” by Gibbins in posting the comments.

The tribunal document says it concluded Gibbins was seen to have bought the charity into disrepute and sacked not because she expressed a republican belief, but because “she had associated herself with a distasteful and personal attack on a small child”.

The tribunal report says that, although an employer might have chosen to discipline Gibbins without sacking her, no member of the tribunal could say it was unreasonable to dismiss her.

“Clearly the claimant deserves some sympathy for her slip of judgment, but that does not mean the decision was unfair,” the report says.

A British Council spokeswoman said: “While we recognise the difficult nature of this process for all involved, we are pleased that the tribunal has found in our favour in relation to all of the claims. The British Council looks to act with integrity and respect in all that we do to promote the UK and our position in the world.”