The Soil Association’s annual Out to Lunch survey found that 75% of lunchboxes sold at popular attractions did not routinely include a portion of vegetables or salad, while half included muffins, cakes and sweet treats but no fresh fruit.

A poll by the charity showed that only 14% of parents said they thought the children’s food on offer was good enough.

The charity and organic certification body, which supports sustainable food and organic farming in the UK, surveyed the food and drink on offer at 20 of the UK’s most popular family attractions, covering all English regions, Scotland, Wales and Northern Ireland and ranking them in an online league table.

Research was undertaken covertly by parents, as well as via desk-based menu reviews and a questionnaire.

London’s Natural History Museum and Brighton Pier scored joint last place in the league table, while the Eden Project in Cornwall topped the rankings, with Chester zoo in second place. When it came to sustainability and sourcing, only three attractions – Eden Project, Chester zoo and Durham cathedral – could reliably tell parents where their meat came from.

Rob Percival, Soil Association policy officer, said: “Visitor attractions are making life hard for parents who want to enjoy a healthy and happy day out. Lunchboxes loaded with sugar and unimaginative ultra-processed foods are the norm and also a missed opportunity. So long as junk-filled lunchboxes continue to dominate family outings, parents will have a hard time convincing their children that healthy food can be a treat too.”

Anne Martin, managing director of Brighton Pier, questioned the survey results, saying the attraction had not received the questionnaire.

She told The Guardian: “Accordingly, the survey results are inaccurate and unrepresentative of the efforts we have made to offer our customers a choice of healthier, sustainable dining options. The children’s menu in Palm Court was at the forefront of Jamie Oliver’s recent national Sugar Smart campaign when it was launched in Brighton, offering reduced sugar items to children: we have received many compliments for this as a result.”

Below is the Soil Association’s league table, ranking attractions on “food you can trust, healthy choice for children, healthy choice for adults, health choice attraction and eating experience”, with a score out of 150 (lowest ranking to highest, is):

Natural History Museum (21)

Brighton Pier (22)

British Museum (23)

Alton Towers (24)

Stirling Castle (26)

The National Gallery (28)

National Museum Wales (34)

Kelvingrove Art Gallery and Museum (35)

Royal Botanic Gardens Edinburgh (39)

ZSL London Zoo (45)

Stonehenge (46)

Mac Birmingham (48)

Millennium Gallery Sheffield (52)

Wales Millennium Centre (52)

Royal Botanic Gardens, Kew Gardens (54)

Titanic Belfast (65)

ZSL Whipsnade Zoo (76)

Durham Cathedral (79)

Chester Zoo (81)

Eden Project (97).