I’m not sure what your claim in brackets means. Margaret Thatcher was British Prime Minister in 1979.
It’s true for a given set of parameters: Vigdís Finnbogadóttir was the world’s first democratically elected female President. Margaret Thatcher was a PM, not a President. Isabel Peron was President of Argentina in 1974 but wasn’t democratically elected. Etc etc.
I recommend this site to you for all women leader factoids. I don’t know if there’s an equivalant homosexual leader site.
Yeah, I meant what Gyrate says.
Can you even have an affair with a corpse? I would think “affair” implies consent.
But Obama is HALF black and HALF white.
To be consistant Iceland would have to have a bisexual PM
Madame Johanna?
In that case I bring to you her previous marriage to a man and she even had kids with him.
Ha! 
Sure.
Per-Kristian Foss was briefly acting Prime Minister of Norway in 2002.
James Buchanan, “the only bachelor US President”, had a lot of rumors around him - but he wasn’t out, so he doesn’t count.
Damn Norwegians, stealing the win 
Thereby definitively ruling out Ted Heath as a possible candidate. Though, as his Wikipedia entry notes, the matter has never risen above the level of gossip and the author of the acclaimed standard biography of him was unconvinced by the rumours.
Well, if you had done years of research on Heath’s life and failed to notice his (alleged) homosexuality, you might want to consider pooh-poohing the rumours too.
A couple of years ago the Parti Québécois acquired the first openly gay leader of a political party with seats in North America, André Boisclair. Unfortunately he turned out to be a joke and led his party to a swingeing defeat in the 2007 election, and he was certainly no friend to the actual LGBT community. (He’s since been replaced with Quebec’s first female Leader of the Opposition.)
At least two other parties without seats have had LGBT leaders in Canada: Chris Lea was the leader of the Green Party in I believe the 80s, and Allison Brewer led the New Brunswick NDP in the mid-00s.
Though both were married, so its hard to describe them as “out”.
So, what about Svend Robinson and Scott Brison, two other openly gay MPs?
ETA: And am I the only one who had to look up LGBT?
They didn’t lead their parties.
Ah, mais oui.
To expand on this a little, Svend Robinson did campaign for the NDP leadership in 1995 but was defeated.
He actually won the first ballot (IIRC) but decided to drop out of the race in favour of Alexa McDonough. This was before my time, though.
There are currently six MPs who are out members of the LGBT community: Bill Siksay and Libby Davies in the NDP; Scott Brison, Mario Silva, and Rob Oliphant for the Liberals; and Réal Ménard for the Bloc. Out gay former MPs include the NDP’s Svend Robinson and the Bloc’s Raymond Gravel.
Svend Robinson was the first out gay MP (February 29th, 1988 – his constituency office had all its windows smashed), Libby Davies was the first (and so far only) female MP to come out as having a female partner (although she doesn’t label her sexual orientation), Bill Siksay was the first MP to already be out when elected to a first term, and Scott Brison was the first out gay cabinet minister.
Interestingly, of these, Rob Oliphant is a United Church minister, Raymond Gravel is a Roman Catholic priest, and Bill Siksay was a candidate for United Church ordination (his partner is a UC minister).
There are a couple more MPs and former MPs whose sexual orientation is just about as open as secrets get, but who have never officially come out. Ottawa can still be a pretty closed town in several respects.