Too many children will wake up on Christmas Day in a “cramped hostel room or a run-down bedsit”, a homelessness charity said as it launched a campaign to raise awareness of young people living in temporary accommodation.

Shelter has unveiled a 90-second film in the style of annual festive television adverts – but the seemingly feel-good short ends with a stark reality.

The film, Good As Gold, follows eight-year-old Maddy – played by an actor – who is shown on her best behaviour and helping others in the hope she can have the gift of a home for Christmas.

The warm-hearted advert concludes with the child waking up in a confused state on December 25 to the realisation she is still in a grotty, one-room accommodation with her family, as she utters the words: “But I was so good.”

The numbers of households and children in temporary accommodation in England are at record highs, government statistics released in July showed.

Some 104,510 households were in temporary accommodation by the end of March – the highest number since records began 25 years ago.

The total number of children in this situation is also at the highest level since records for that measure began in 2004 – with 131,370 children living in temporary accommodation as of the end of March this year.

Shelter chief executive Polly Neate said: “This advert brings to life what it really means for a child to have nowhere to call home.

“Make no mistake: a cramped hostel room or a run-down bedsit is not a home, but this is where far too many children will be waking up on Christmas morning.

“As we head into winter, Shelter is doing everything we can to help the thousands of families facing homelessness this Christmas.

“Our expert advisers are working in communities across the country, they are taking calls at our emergency helpline, and they are providing free, expert case work.”

The advert, which is being sponsored by Shelter’s partner HSBC UK, will run across television networks throughout the winter period.

Shelter said the creative agency Don’t Panic worked closely with people with lived experience of temporary accommodation, who cited damp living conditions, mould on the walls, an entire family sharing one bed and the emotional impact on families in those situations.

The charity has appealed for donations to support its work via www.shelter.org.uk/donate.