Need Advice with neighbours on Herring Gulls and their fledglings! Please help.

For several years now, my neighbourhood has been graced with the presence of a small colony of Urban Herring Gulls. This year, a couple chose my flat roof as their new home. As time passed, the devoted gull parents successfully cared for their offspring, resulting in the growth of two healthy and lively fledglings. However, one of the fledglings accidentally flew into my neighbour's garden mid-flight practice. (I will note, their garden is the perfect space for young gulls to practice flight, with good space, grass, shade, and predator-free surroundings.)

Not only did I inform my neighbours, but I also mentioned that this is expected behaviour for young gulls during this month and that it is nothing alarming. (I did offer various solutions, such as carefully relocating the gull into my garden, yet they declined.) 

Over the next two days, both gull parents have shown unwavering dedication, taking turns to watch over both fledglings (roof and garden), ensuring their safety and well-being. However, when I returned from work today, I discovered that my neighbours had taken the liberty of completely removing the young gull from their premises. This act has left the parents in a state of distress, and they have been continuously searching for the said fledgling, consequently setting the entire colony of gulls into a small frenzy. 

Of course, I am upset that my neighbours have decided to take such drastic action. I would appreciate any advice on how to better handle this situation for the future, as I am worried for the remaining fledgling (that is still on my roof). 

I do not know who they called to have the fledgling removed and taken from their parents, but I was informed that they took the young gull to a wildlife hospital (two hours away).
They also mentioned how the gull wasn't injured, but they felt as though it was the right thing to do. 

For background information, the Urban Gulls in this area are very different from those found in other major cities or coastal areas. They prefer to avoid humans as much as possible, unless it's to protect their young. They don't even rummage through the neighbourhood bins! They're honestly the politest gulls I have ever met. So, to think, this sweet fledgling, only 45 days old, has been taken from its parents and brought into a completely different habitat. In a completely different city... I just do not want a repeat of this situation. 

Summary: Gull parents nested on my roof, raising two fledglings. One fledgling accidentally flew into the neighbour's garden. Despite my efforts, my neighbours removed it, leaving the parents distressed. Worried for the remaining fledgling's safety. Any advice would be greatly appreciated. 


Note: I know most people in the UK hate Herring Gulls, but this is not the time for hateful opinions. So I kindly ask you to refrain from commenting here. Thank you.