Phil Smith is to retire as the British Horseracing Authority's head of handicapping after 22 years' service.
He will step down from his role in May 2018 in preparation to leave the regulatory body next July.
Smith, 68, joined the then British Horseracing Board in August 1995 as a Flat Handicapper. Four years later he was appointed as senior National Hunt handicapper and in January 2007 became the BHA's head of handicapping, a position he has held since.
Smith has been responsible for a number of significant advancements in handicapping practice. These include the introduction of the Anglo-Irish Jumps Classification in 1999-2000 and recently achieving European agreement to make an adjustment to the Flat weight-for-age scale for the first time in over 20 years.
He was also responsible for changes in handicapping practice in the Grand National, introducing 'compression' at the top of the weights in order to give higher-rated horses a more realistic chance of being competitive in the world's most famous steeplechase.
Smith said: "I have really enjoyed my time as an official handicapper. Although I will be moving on from working full time as the head of handicapping, I hope to continue my international commitments and to stay involved in racing utilising the skills and knowledge I have gained over the last 20 years or so.
"During my time at the BHA I have tried to make the methodology and decision making process of handicapping interesting, clearer and less complex, both with explanations of our decisions in the media and to trainers and owners.
"Of course, not everyone has agreed with me all of the time, but that is part and parcel of the job and I can only hope that I have tried to make our methodology as open and understandable as possible.
"For the last 10 years I have been supported by a fantastic team and a brilliant deputy in Dominic Gardiner-Hill and I know they will develop and continue to modernise British handicapping.
"Most importantly I am looking forward to the upcoming winter jumps season and despite my stepping down next year, it will be business as usual."
Richard Wayman, chief operating officer for the BHA, said: "Phil has been a brilliant leader of our handicapping team, passionately committed to being consistent, fair and even handed with all horses at all levels and, in doing so, making handicaps as competitive as possible.
"His influence extends beyond Britain and he has made a major contribution on the international stage. We'll also miss his expertise in other areas such as the race programme and race conditions, including, most recently, the changes to the weight-for-age scale.
"We will now commence the process to find the next head of handicapping who will be responsible for the future leadership, structure and policies around handicapping in Britain."