There's been growing anger among Ethiopians in and outside the country, about the way that some of their compatriots have been treated in Saudi Arabia. Things came to a head following an ultimatum for illegal migrant workers to leave the country. And there were clashes in Riyadh which led to several deaths last week. On Monday, there have been demonstrations at Saudi embassies around the world. The BBC Africa's Kasim Kayira went to the one in London.