Behind the scenes it was a hoot. The crowds had turned up and the security staff were in place - but they couldn't get the curtain open.
By David Sillito
BBC News arts correspondent
Hundreds queued for hours ahead of the launch
Britain's most successful model was looking decidedly uncomfortable as a burly man in a cubby hole frantically tried to get the pulley to work.
By the sides, Topshop tycoon Sir Philip Green was shouting a few encouraging words, and so too were a number of the hundreds of photographers waiting to cover the revealing of a window display.
Oh well, fashion is never on time and eventually the curtains did part to give everyone a sight of Ms Moss. Well, only if you didn't blink.
The biggest photo opportunity in Topshop's history finally got under way - and it was over before most had realised it had started.
Inside, Ms Moss walked off to a corner and Sir Philip told the invited camera teams to
keep away - she was having a quiet moment.
Meanwhile, unaware of any of this, there was the crowd of shoppers who had been waiting for more than three hours.
The signature look was outsized dark glasses, skinny jeans and a slightly surly appearance. They had all learned well from their style mentor. There was none of the pushing and shoving of the recent Primark launch on
Oxford Street - they were too cool for all that.
One chap, who was perhaps not a size eight, assured me he was buying clothes for his girlfriend. He had orders for 17 items. "I'll have to go through a few times as you are limited to five items for each visit," he said.
Another young man emerged later with a T-shirt which had not been designed for a bloke, but he needed at least a memento of his evening.
His friend showed me her haul. She was disappointed, saying that she felt it was over-priced and many of the items she had seen in the press had not yet been released.
Nevertheless, none of this stopped the buying.
So what was this all about? Well, the collection is inspired by Ms Moss's own wardrobe. The smock tops, skinny jeans and hot pants and sunglasses are now part of the High Street uniform of a certain type of young woman and they are all styles that are linked with Ms Moss.
Fashion retailers can spend millions on getting posh models to wear their outfits, but few are as successful as Ms Moss wearing something in a field in Glastonbury or draped around her boyfriend Pete Doherty.
This amazing selling power was being tapped into directly and many of the people in the queue were quite happy about the process. It was all about the aura of her cool persona.
'I love Kate'
It's not just about beauty or clothes.
This was a cult and her devotees were happy to write '"I love Kate" on their faces even though almost none of them had seen her in person. Nor has she given away any of her secrets in interviews.
Ms Moss appeared in Topshop's window at the start of the launch
She exists, for most, only in photos - impossibly glamorous glimpses of an exciting bohemian life. Perhaps
that's what's so great about her.
Anyway, there was no real frenzy.
If you block any pavement on Oxford Street you'll get a bit of shoving, but it quickly passed and most of the chaos was created by people trying to get past the media throng.
Shoppers in the queue that had snaked around the block were calm and well-behaved and the numbers soon thinned out.
Ms Moss, meanwhile exited down the escalators, closely pursued by some photographers.