The Houses of Parliament are being lit up in rainbow colours for the first time this weekend to mark Pride in London.
An image of the flag will be projected onto the riverfront of the Palace of Westminster.
Aberdeen South MP Ross Thomson said the step sent a “clear and public sign of support” to the LGBT community around the world.
The former councillor, who is in a civil partnership, added: “The illumination of the historic Palace of Westminster overlooking the Thames – an iconic sight recognised across the globe – is just one of a series of events planned over the weekend.
“It is interesting to note that the UK Parliament now has the highest number of LGBT+ politicians in the world – which is testament to how far we have come in this country.”
The rainbow flag is also flying over Portcullis House, the newer part of the parliamentary estate.
Lords Speaker, Lord Fowler said the “stigma and discrimination” affecting gay men and women remained “one of the most urgent issues today”, pointing out homosexuality is still illegal in more than 70 countries around the world, including many in the Commonwealth.
He added: “The situation has improved in Britain over the past few years, though few would say that all hostility has been overcome.”
He said none of this would be “solved by a march or display of lights”, but added: “These acts will demonstrate to those who are being persecuted or abused that they are being supported.”
Other events planned include Pride at Parliament tours, highlighting the significant part played by LGBT people in parliament.
They will also mark 50 years since the passing of the Sexual Offences Act 1967, which decriminalised private homosexual acts between men aged over 21, while at the same time imposing heavier penalties on street offences.
The law was not changed for Scotland until 1980, or for Northern Ireland until 1982.
In 1994, the Criminal Justice and Public Order Act lowered the age of consent for gay men from 21 to 18, and it was further lowered to 16 in 2001.
Additionally, the UK Parliament will be taking part in today’s parade.
David Geary, head of political engagement for Pride in London, said the institution had become a “powerful tool for equality in recent times”.
He added: “The illumination of the Palace of Westminster demonstrates the resilience of the torch which burns for global equality.”
