Splendid Isolation- when Britain played little part in events in Europe. It remained isolated from any alliance in Europe as long as no single power gained complete control.
The British government followed this policy because they didn't want to get involved in foreign affairs and they wanted to focus on their navy and empire.
Splendid isolation depended on the strength of Britain and whether they needed help from other countries.
Britains rivalries changed at the start of the 20th century because at first Britain and Germany were natural allies because their royal families were related but then Germany started to build a navy which confused Britain because Germany already had the strongest army. Also Britain became involved in the Boers war in south Africa which lasted 3 years and Germany expressed views which annoyed Britain.
It made Britain question its policy because Germany built up their navy and the kaiser made his views public about the Boer war which annoyed Britain.