All-girl couples stage 'kiss-a-thon' in Barcelona

The demonstration, which started with a 'kissing chain' in the Plaza de la Universidad, was organised by the Catalunya union of students, and spokeswoman Anna Roselló read a manifesto in which she explained the importance of lesbian visibility, and spoke out against discrimination and 'being forgotten' in 'every walk of life from the classroom to the streets'.

“Education will never be truly public until women, lesbians, the poor, and transsexuals are in the textbooks and until we combat the injustices we suffer every day,” Roselló announced.

A women's group has also denounced the 'lack of sexual health information' available to lesbians, which coincides with research published by UK charity Stonewall revealing that an overwhelming majority of women who have relationships with other women have 'no idea' about how to practise safe sex, and that gynaecologists are generally unaware of the issues they face that differ from those of heterosexual women.

Some complain of being tested for ectopic pregnancy or miscarriage despite telling the doctor they are lesbians and that an unplanned pregnancy is impossible.

Spain is widely known to be one of the world's safest and most aware countries for homosexual and bisexual visitors and residents, and open homophobia – whilst it does occur and attacks have been reported – are extremely rare and treated very seriously by authorities, with even verbal discrimination or insults potentially leading to arrest.

It was also the fourth country in the world – pipped at the post by Canada – to legalise marriage between same-sex couples and enshrine in law their identical treatment to mixed-sex couples, especially in terms of adoption and childbirth.

Whilst lesbians could not get married in the UK until 2014, all-girl couples who tied the knot in Spain on the day it became legal were, by then, celebrating their ninth wedding anniversaries.

Stonewall and similar associations have always explained that 'discrimination' for homosexual women is different from that of gay men – the latter are more likely to be ostracised by same-sex friends or suffer violence in public, especially at the hands of other males, whilst lesbians suffer 'invisibility', being 'forgotten' or 'going unnoticed', often feeling they do not exist in society's eyes which, although less troublesome than physical aggression, has a negative impact on emotional and physical health.

Statistics have shown in the past that lesbians are more likely to die from cervical cancer than heterosexual women since, although their risk is much lower, they believe they do not need regular smear tests or have even been told by the medical profession that it is unnecessary – another side-effect of lack of information available to lesbians.

Spain has long since addressed this, and doctors will advise all women to take regular smear tests irrespective of their relationship status and even if they have never had a relationship with either sex.

Photograph by the Sindicat d'Estudiants dels Països Catalans (Catalunya Nations Union of Students)