What's all this? Had to negotiate a police search for knives on entering Kensington Gardens this afternoon. Apparently a fairly regular procedure, done to "assure the public", the officer on duty said. I'm not sure it had the intended effect.

The greater problem inside seemed to be the number of dogs running around, even around the Long Water, where several were (illegally) worrying the birds. One regular user of the park told me that dogs have killed seven swans in the park already this year. And they say bicycles in parks are antisocial...?

Still, the trees were looking nice.

Westfield London, the vast new £1.7bn retail development at Shepherd's Bush, opens tomorrow. And, would you believe it, the planting has been left till last. I'm told landscapers LDC were round at specialist nursery Tendercare even at the weekend, looking for "big stuff". And passing by the site this afternoon, with less than 24 hours to go, I saw massed ranks of hi-vizzed contractors still busily planting up:

According to the Telegraph, it's a "vintage year" for autumn leaf colour, thanks to the recent fine weather. This certainly seemed to bring out visitors to Winkworth Arboretum in Surrey at the weekend, which boasted one of the finest displays I can recall seeing - I'm not sure my photos do it justice.

If any readers have spotted other attractive displays this season, do send your pics to the usual address, and I'll add them to the gallery.

Wandering around Amsterdam's Horti Fair, which closes today, can be inspiring, but also a little disheartening. Even in a tough year it is awash with bright young things proudly displaying solutions to what most of us hadn't even realised were problems. There was a Latvian firm using nanotechnology to tweak the light transmission of glass to optimise protected crop prodution. There are a few Brits among them with unique niche products that attract international interest, but generally the cutting edge stuff comes from the Dutch.

Did it have to be like this? The Dutch undoubtedly gain from a close-knit network of small companies, banks and research establishments, as well as a supportive government. Perhaps the high pressure on, and cost of land is a goad to innovation. But the upshot is that a culture of engineering and manufacturing has been maintained there that has largely disappeared in the UK. This can be seen on a visit to any Dutch production nursery, where much of the kit will have been designed, commissioned, maintained and even built by the nursery's own workforce.

Not so long ago, James Dyson, who had given up trying to manufacture his vacuum cleaners in Britain and relocated to Malaysia, lamented this loss of British nous:

In the 1970s, when I was developing the Ballbarrow, I needed some bent metal tubing. I got in my car and went to Birmingham. In the space of a few streets, I found workshops and suppliers who between them could provide the tubing, cut it, bend it and coat it. It was an extraordinarily vital environment. And it was absolutely essential to the small engineering entrepreneur.

You might ask what happened to these British suppliers and subcontractors? Quite simply: we drove them out of existence. Employment and property laws made it difficult for them to take on extra staff and premises. They needed a tax regime that appreciated the volatile nature of their business. Instead, Governments imposed PAYE and hammered them with high interest rates, year after year. By the mid-1980s, most had gone to the wall.

Of course this wasn't thought to matter at the time, as the great service sector economy would, as it were, hoover up all the labour and investment.

Sadly it now appears we can no longer keep getting richer simply by selling mortgages and pensions to each other. Yet with the loss of skills, infrastructure and experience, we won't be able to just switch back to making things either. As Dyson foresaw:

Britain's service industries will wither without their manufacturing customers.Innovation will be stifled.We will be surrounded by products that we have not made. That's something that is already culturally destructive.

The 150th anniversary conference of the London Natural History Society was highly informative but also a little sad. The capital's flora and fauna are changing at an alarming rate, yet working out what exactly is going on where depends on little platoons of volunteers going to the trouble of recording sightings.

Unfortunately - and I don't think I'm doing too grave an injustice to the good people of LNHS here - they're all getting on a bit. It must be a worry that when these doughty sorts stop perusing London's green spaces, notebook and magnifying glass in hand, we'll have less evidence on which to base environmental policy, just as climate change is taking visible effect.

Prof. David Goode of UCL acknowledged the problem but reckoned the internet was a potential source of new recruits. Well if that's you, he is contactable here.

Waltham Forest's "borough wildlife crime officer" Sgt Rowan Healey seems to have a bit of time on his/her hands. S/he has urged the public to report any squirrel-drowning incidents - allotment holders are apparently under greatest suspicion, although no such incidents have yet come to light.

Being caught drowning Tufty can apparently lead to six months in prison or a £5,000 fine under the Wild Mammals Protection Act. But wait a minute - it's also illegal to let them go, says the Wildlife and Countryside Act. So had my uninvited guest the other week failed to find his own way out again, it seems legally I could neither have released him nor dispatched him. Not sure what that leaves - can squirrels be house-trained?

Further to my earlier thoughts on grey squirrels, London Wildlife Trust vice-chair Mathew Frith reckons we should just learn to get along with them.

"There have been no red squirrels in London for decades," he told a meeting of the London Evolutionary Research Network. "The grey squirrel is London's squirrel. They undoubtedly have an adverse effect on the reds. Aside from the disease they carry, they have more catholic tastes and are just generally fitter."

It comes down, I suppose, to what you regard wildlife as "for". Frith says interaction is what's important. "Feeding the greys is a key interaction between wildlife and the public in London," he said, adding the same went for Canada geese.

"I'm not purist about where things come from," he said. "The amateur naturalist tradition in the UK is superb, but there is an anti-people element at the fringe, among the ‘deep greens', and hints of xenophobia."