Detectives investigating the murder of 81-year-old Léa Brooke are still struggling to find a motive for the arson attack which claimed her life.

Yesterday Det Supt Dave Pervin launched the poster campaign at St Peter and St Paul on St George's Walk, Wakefield, where Mrs Brooke worshipped and which she visited the day before her death.

He told the YEP: "It's now three weeks since the fire and it's still unclear as what a possible motive could be and why anyone would want to do this."

Mrs Brooke, who has five children and 12 grandchildren, was killed at her home at The Old Coach House, Sandal Grange Farm, on Walton Lane, Sandal.

At around 1.30am on November 10, someone poured a flammable liquid through the letterbox and ignited it.

The huge blaze that followed gutted the 25-year-old building and it took dozens of firefighters to bring the flames under control.

They later recovered Mrs Brooke's body from the house.

The posters will be distributed to shops and premises around the area as Det Supt Pervin admitted that the public response to appeals over the fire has not been as strong as hoped.

He said that police were still to trace a white box van which was seen going down the drive to Mrs Brooke's home at around 4.30pm on Sunday November 9. It is described as rusty on top.

And they are also still looking for a man in dark clothing seen walking along Walton Lane – towards Barnsley Road – on the right hand side pavement close to the turning into Sandal Grange Farm.

Det Supt Pervin said: "That man will have been aware of the fire and will have seen the fire engines."

He said that police still thought it was possible Mrs Brooke's youngest son Howard, who ran a construction company from the house, may have been the target.

He added: "The answer to this crime is likely to be in the community. Someone in the community will have vital information as to why this happened and no one has come forward. I hope they will see these posters - in shops, community centres, supermarkets, pubs and sports centres - and ring us and let us know what they know."

Mrs Brooke, who was originally from Belgium and settled in Wakefield, was an active member of the Inner Wheel Club of Wakefield and had been the district president. She was also a member of the Ladies' Luncheon Club, The Flower Club and The Civic Society.

Anyone with information is asked to contact the police incident room via 0845 6060606 or Crimestoppers on 0800 555111 or text to 07786 200 806 followed by "Sandal Fire" and your message.