Police are advising drivers to avoid the M25 until mid-afternoon after a lorry fire closed the carriageway on both directions in Hertfordshire.
The section between junctions 21a and 23 near the South Mimms services is expected to be closed until 3pm.
Long tailbacks have built up on surrounding roads.
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A windy evening, clear spells and a few blustery showers. Strongest winds are likely along coastal areas.
Around 170 officers and staff from Cambridgeshire police, were drafted in to manage the demonstration.