You live in London and you've applied for jobs asking for sexual orientation? I live in the UK too and I've never seen that anywhere I actually thought it was illegal.
I'd say all but maybe two of the jobs I have ever applied for have asked for it. (I live in the UK too.)
I've seen this happen a few times (I live in the UK).
I'm honest and say I'm gay, why shouldn't I? To deny or refuse to answer the question would be adding to the problem and the idea that it's something to hide or be ashamed of.
Yeah it must be an England thing as I've been asked this countless times on applications.
It's purely for equality reasons. I know some will tell you otherwise but I have heard and seen experiences of where being a minority can actually aid your application.
My friend is high up in a manager type position in a big store over here and they'e told to make sure to try and hire people from diverse backgrounds (people of different ethnicities and sexualities etc)
But anyway to answer your question I always answer gay. When i was younger though I did get a bit scared I'd be penalised for it though and would sometimes just tick straight.
They never put it on the main application, but sometimes they have an "equal opportunities" section. These sections aren't used to discriminate against you, it's more the opposite, they're used to monitor who companies are hiring and to make sure they're being fair. The "equal opportunity" forms are never sent to your interviewers, so nobody will actually see the information you provide, they're actually sent to human resources and filed away for monitoring.
But there is usually a "do not wish to say" option and it's entirely your right not to disclose such information.
They simply don't do this in the United States. I didn't even know places outside of the United States would ask such questions on job applications. The common job application in the United States would ask for Name, Address, Phone number, Sex/Gender info,Race/Ethnicity info, Emergency contact, Email(optional), Educational background, Work History, and Criminal Criminal Background questions. Some of the applications also feature questionnaires that describe attributes a person asks and how to resolve certain situations.