In Victorian times it was not uncommon to see two posh gentlemen arm in arm, or two working class pals with their arms over each others shoulders. In those days, it was not thought of as homosexual. With homosexual liberation in the 1960's came a lot of homophobia and paranoia too. So men just don't do that any more.
Everton is right. Of course it is all to do with homosexuality. I am from Pakistan and there good friends still walk holding each other�s hands or arm. However after spending 19 years in Britain even I sometimes feel about it whenever I go back but only for few days. I did not like when my 11 years old son tried to pull his hand out of my hand while walking in the high street one day. I knew why he was doing that as children now a days know about it all at very early age. So to give him an insight about this I told him a very simple formula.
I told him that people in Pakistan introduce you to their friends calling them as their brothers and not friend. And you do not have sex (most probably) with your brother. So that friend stays as brother and does not become friend or a partner. Once that mystery is solved then you hold arm or hand, does not make any difference.
You probably wouldn't question a group of blokes walking arm in arm having a sing-song at about 11:30 at night after the rugbys finished. Sometimes context helps.
Only seen the family of my Turkish neighbours holding hands but more usually linking arms. They do it with hubby - lol. He tries to shake them off funny to watch