DEATH can often seem like an ending but when heroic World War Two pilot Lionel Anderson was shot down and killed in action it set off a spark inside his younger brother that would ignite his imagination for years to come.

A new book by Sarratt author Sean Feast reveals how the daring Englishman’s real life exploits inspired his famous sibling Gerry Anderson to create his adored Thunderbirds television series and how Lionel lived on through almost all of his characters.

Thunderbird in Bomber Command tells of a young man who flew some of World War Two's most secretive and dangerous missions.

“He was an incredibly brave man and I have written about a lot of war heroes, " says Sean who has penned more than a dozen books about pilots from that era.

His latest is based on letters Lionel wrote to his parents Joseph and Deborah Anderson and younger brother between 1941-43. They detail his journey from Manchester to Arizona where he learnt how to fly and mingled with film stars and his return to England to fight the Nazi's. The 70 or so letters end when he started active duty, as part of the Mandrel missions to jam German radar signals.

Along with an album packed with photos of his adventures, they remained locked way at the bottom of a trunk for years-only coming to light after Gerry died in 2012.

Sean met with Jamie almost a year ago to discuss turning them into a book and says: “It was one of the easiest decisions I’ve ever had to make, I knew that it lent itself to a great story.

"It has everything really, the interest of a young man sent out to America to train, mixing with the Hollywood stars, and then coming back and flying very secret operations and then the impact that had on his younger brother which ultimately prompted him to create the wonderful series of the Thunderbirds.”

Lionel's letters reveal how he was swept up in the adventures his new home provided.

“He very much liked his women and talks a lot about the girls he meets. He is very excited about life and opportunity to fly some of the most modern aircraft of the time. It doesn’t get much better for a 19 year old than training to be a fighter pilot and that really comes across in his letters.”

Many fans believe Thunderbirds was named after the US Army Air force base named Thunderbird Field No. 1 in Arizona that Lionel mentioned in one of his letters but Sean says it was actually inspired by the 1942 propaganda film Thunder Birds that was made there starring Preston Foster and Gene Tierney.

“Lionel and the other pilots were all used as extras and he writes at some length about taking part. They were all on screen marching passed in glorious technicolor in this wonderful film and of course it fired Gerry’s imagination.

“Can you imagine the whole thing? A Hollywood director coming to film, and his brother talking about how he is flying the latest aircraft and all his crashes and thrills and spills- if you are 12 year old boy and you are reading this stuff from your older brother who you clearly hero-worship- you can see how it had a profound effect on him.”

During filming Lionel became friends with Preston, who invited him to go to the Hollywood film studios with some friends.

“They were entertained absolutely royally, “ reveals Sean who grew up in Hertford and went to Haileybury school.

“ He got to dance with Joan Fontaine and said how lovely she was, he met Judy Garland and some of the other biggest stars of the time.”

Lionel’s letters came to end when he returned to England and after further training for wartime conditions began flying missions and it is what happened next that Sean had to spend hours researching and piecing together using public archives, private correspondence and through one of the survivors who he tracked down in New Zealand.

He discovered the Mandrel missions involved Lionel flying a two seater aeroplane back and forth over the coast of France while another man in the back used secret equipment to jam the German radar, allowing bombers to pass safely into the enemy airspace.

“The operations he flew were part of a very secret war, of which very little has been written about and very little is understood. So that was an eye-opener even to me,” says Sean who’s first book Flying Through Fire was written about his great uncle, Flight Sergeant Peter Noble.

“These flights were undefended and couldn’t be contacted from ground control, so no one could let them know if there were German night fighters about. It couldn’t be more dangerous. They were effectively flying blind for over an hour, and not surprisingly the loss rate was very high.”

Lionel completed more than 30 operations, over 100 hours flying, helping prevent hundreds of English planes from being shot down, and his squadron was then re-equipped to the twin-engine Mosquito and started another series of missions as intruder forces, flying ahead of the bombers and shooting up enemy airfields so the bombers faced less opposition.

“Again that was incredibly dangerous,” says Sean, “and his squadron 515 suffered one of the highest losses for those types of operations. "

Lionel was tragically shot down and killed on one of these missions on April 27, 1944, aged just 22 and his death meant Gerry lost more than just his older brother.

Sean explains: “Lionel’s mother had almost a dangerous love for him and when he was killed she turned to Gerry and said ‘it should have been you’.

“Which is why on Tracy Island there is a dad, five boys and no mother figure and in fact in nearly all of things Gerry Anderson did there is no mother figure. The family told me he never forgave her for what she said.”

He also never forgot Lionel, keeping his album and letters against all odds.

“Jamie says his dad was one of those people who never kept anything," says Sean. "so it’s quite remarkable that these letters survived. For some reason Gerry didn’t throw those out.”

The 48-year-old author, who grew up watching Thunderbirds, raced to write the book in just six months, so it could be released to mark the 50th anniversary of the Thunderbirds and Jamie Anderson told him his father would have been proud of it.

“People have often talked about Gerry Anderson being influenced by his elder brother but I don’t think anyone realised the extent to which he was influenced, “ says Sean who by day is a director of international PR and advertising agency Gravity London.

"The family home had a huge portrait of Lionel hanging in it and in Tracy Island you will see all these big pictures of the boys.

“And I do think Scott Tracey who was the all-singing dancing hero of Thunderbirds was very much modelled on Lionel and indeed all of Gerry’s hero characters have a little vignette of his brother in them."

Thunderbird in Bomber Command is now now. Details: seanfeast.com