Parents of Alfie and Harry McQuillan describe what happened when they discovered the overdose of morphine had been given.
One twin was given ten times the recommended dose while the other twin was given 17 times the normal dose.
Both died soon after the drug was given.
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Virgin West Coast, which runs train services through the West Midlands, is the least punctual rail company in the country.
It will be very warm today with some thundery showers.
It will be cloudier and less hot than yesterday but with thundery showers for some.