After a steep climb through dense forest, the stark reality was that we were face to face with a hawk trap, calculated to catch one of the most magnificent bird of prey on the planet, the goshawk. And all within a stone's throw of thousands of tourists, enjoying the splendour of the most popular national park in the world.

Our pre-dawn arrival was full of stealth and purpose: a covert camera was quickly deployed and we watched from the shadows.  

Shortly after eight, we heard the distinctive snapping of branches underfoot and a figure began moving through the trees towards the trap. Once in full view, a combination of his distinctive appearance and the fact he was carrying a gun gave away his identity and motive. It was Glenn Brown, a gamekeeper on National Trust land since 2006.

The cage trap was the size of a garden shed, made of wood and mesh and containing a funnel entrance through which the target species could enter on a one-way ticket. The trap is legal when used with a live crow or magpie decoy, but most certainly not when the sacrificial prey is a live domestic white pigeon - the equivalent of Christmas dinner for a goshawk.

We watched him approach the cage, immediately checking for the pigeon which at once radiated life and blissful ignorance. The disappointment on Brown's face was clearly visible - no raptors today.

He returned the next day, same time: status quo, the pigeon was still alive, the raptor count was nil. The evidence of a previous day's campaign was all around, hundreds of white pigeon feathers strewn the bottom of the trap and the bodies of a white pigeon and a sparrowhawk lurking nearby. The underside of the sparrowhawk's tail was caked in faeces, a clear sign of its recent confinement in the trap.

On Saturday morning the situation changed suddenly. The covert camera caught the usual arrival, just after 8 am, but this time it was a camouflaged man wearing a full-face balaclava. His actions were deliberate and decisive, the white pigeon was released and the trap skilfully disarmed. Weekends are manic in this valley - tourists delve in to even the most unlikely places - and it was just too much of a risk.

At that moment, the white pigeon was the most important bird in the valley; it was the transporter of vital evidence, as its wings had been marked in a unique way by the RSPB.

The satisfaction was audible when three days later it was discovered in the pigeon loft of nearby gamekeeper Glenn Brown during a Derbyshire Police search warrant. Its homing instincts were as primeval as the glint in the eye of the goshawk we had just saved.

What happened in court?

Yesterday, after a 10-day trial, gamekeeper Glenn Brown was found guilty on all seven counts relating to this incident. 

District Judge Goulbourn said: 'This was a serious offence against wildlife' and handed down a one-year community sentence and ordered Brown to pay costs of £10,000.

This has been one of the longest trials RSPB have ever been involved in and we thank Derbyshire Police, the CPS and barrister Rod Chapman for their support.

There is history in this the Upper Derwent Valley.  A previous gamekeeper was prosecuted for destroying the eggs within an active goshawk nest in 2002.

Since 2006, goshawk and peregrine productivity has collapsed. There has been only one successful goshawk nest from 20 attempts, pointing to undoubted systematic and relentless persecution. 

Our work here needs to continue. We need your support.