RAF athletes have been battling challenging conditions while taking on runners from the police, civil and fire services for the annual Sir Sefton Brancker Trophy.
Victory would be all the more special for those taking part in the cross-country event at RAF Halton, with it taking place in the Air Force's centenary year.
119 men and 40 women descended on the Chilterns for the 88th edition of the competition, always a great opportunity to get some early season miles in the can.
The course was extended this year, with the men doing three and a half laps.
Taking up the mantle from the front was the civil service's Chris Smith, who hadn't run this race for several years.
With no Ben Livesy or Luke Pollard here, his chief rival was the RAF's Senior Aircraftman Michael Kallenberg, whose focus now is on marathon running.
Smith, who was also the leading veteran, produced a dominant winning time of 35 minutes 53 seconds, just under a minute quicker than SAC Kallenberg. He said:
"I really enjoy the course. It's got a mixture of everything... I love the hills and I love the little jumps.
"I got into a good rhythm. We had a good little battle at the start and I just pushed on the hills."
SAC Kallenberg, meanwhile, said: "I tried to go with him first lap and he just took off. I couldn't live with him today. He was a different class.
"But I'm happy with the run overall, I'm aiming for the London Marathon this year so it's just about getting out and having a good race sometimes."
Marc Hobbs, of the civil service, was fourth and Rob Wood from the RAF fourth.
The RAF, though, won the men's team race with the civil service second and the police third.
The challenging course, with long exposed stretches, plenty of climbing and twisty and very muddy wooded sections, was a real test in ever-changing weather.
No less so for the women, who also ran an extended distance of two and a half circuits. Unlike the men, they enjoyed rather more benign weather conditions, however.
At the front there was a real battle from the off between Natasha Steel, of the civil service, and the RAF's Tamsyn Rutter, a winner of this race in the past.
Flight Lieutenant Rutter was backed up by a strong RAF team and ultimately broke the resolve of her chief rival to claim victory in just under 31 minutes, 15 seconds clear of Steel and the police's Laura Bickerstaff in third.
The RAF also claimed the team title for a women's clean sweep. Flt Lt Rutter said:
"[It was a] good race. It was the longest route yet for the ladies this time, so slightly more endurance [skills were] needed.
"[There was a] really good turnout today, which is very encouraging for the next few races coming up in the centenary year of the RAF."
Although the RAF's official centenary celebrations don't start until April, Sir Sefton Brancker's founding connections with the Air Force and the civil service make this year's race particularly poignant and he would have been delighted with the turnout.
The RAF will now look towards their own upcoming cross-country championships and the Inter-Services.
Click here, meanwhile, if you'd like to relive the action from last year's race...