The Police Federation says while a significant proportion of officers say they want the right to strike it's not appropriate to do so if fewer than half voted for it.
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Seasonal rains have battered the country since late June with more than 150,000 people affected by floods and landslides.
The bus reportedly hit a tree near Russell Square.
Low pressure will throw cloud and few showers across the UK today, but it will also draw in very warm air from Europe again.