Cowslip which would normally flower in May seen in bloom in December on riverbank near Goole

Sean Stewart was litter picking along the banks of the River Ouse at Hook when he spotted the cowslip close to the M62 motorway bridge.

Cowslips are spring flowers which do not normally bloom until April or May - and Mr Stewart was astonished to find one during a spell of chilly December weather.

They are widespread throughout the UK and are usually found in grassland areas. A cousin of the primrose, the cowslip is associated with traditional hay meadows, ancient woodlands and hedgerows.

The loss of these habitats as agricultural practices have changed has meant that the population of cowslips has suffered a steep decline and they are now relatively rare.

In the past, fields full of nodding yellow flowers were a common sight in the countryside.

Cowslips also feature strongly in English folklore - they adorned May Day garlands and were strewn on church pews for weddings. Their name is derived from 'cowslop' - a cowpat - because they were so frequently found in meadows.

According to the Wildlife Trusts charity, cowslips can occasionally flower in December during particularly mild years.