Delays are expected on Sunday when a specialised load transporter carrying a transformer, will be escorted by Wiltshire Police from M4 Membury Services (Westbound) to Melksham.

The transporter and its load, measuring 3.90 metres (12ft-10ins) wide, 4.75 m (15ft-07ins) high with an overall length of 35.60 m (117 ft) and gross weight of 180 tonnes, are expected to leave the service at about 7am on Sunday.

Due to the size of this transporter, which started its journey in Warwickshire, it will be slow moving and will have the potential to create congestion.

A police spokesman said: "Wherever possible disruption will be kept to a minimum but hauliers and motorists are asked to please be patient if they come across this load. Anyone travelling over this period to catch a flight or meet appointments should allow sufficient additional time.

"Whilst travelling on the route listed below it may take up entire carriageways and we ask other motorists to be patient.

"Regular updates and travel information in respect of this abnormal load will be passed from our control room at Devizes when appropriate to help motorists plan their journey."

After leaving the M4 Membury Services, the load will be transported in convoy westbound.

At junction 18 it travels south on the A46, before travelling east on the A420, then south on the A350, turning right on the A4 to Corsham.

It then turns left on the B3109, before turning left again on the A365, passing through Shaw/Atworth before turning left on the B3353, before turning right into Westlands Lane.

The police escort is being provided by volunteer police officers on rest days, paid for by the haulier at no cost to the public.