Picture the scene: a moderately busy suburban branch of a High Street bank in early 2015. A motor cycle courier arrives. He is carrying a large bin bag full of cash, the wads carefully wrapped.

A bank clerk speaks to him as he approaches the counter. “Can you just take off your helmet please - sorry, you know the rules these days. Security and everything."

The courier complies without a murmur. “Where shall I leave the bag miss?” The clerk replies: “Don’t worry love, just leave it on the side, I’ll pop out and get it now."

She walks around to the front of the counter to pick up the bag. It weighs quite a bit, she thinks, and smells a bit musty.

She goes to see her manager who tells her it’s ok, the courier has been before and the company depositing the cash is listed as a long term customer. She takes the cash out of the bag and begins loading it in the counting machine while the Courier waits. It will take some time so he pops next door to Costa for a coffee.

This was no one off. In fact the scene was repeated dozens if not hundreds of times at NatWest branches up and down the country. One day couriers deposited £700,000 at one branch alone in a single day. 

This 'scene' is, of course, my fictitious account of what happened with NatWest’s epic money laundering fail which cost them a £264.8m fine this week from the FCA - and a lot of raised eyebrows. 

It is based on some of the facts which came out in the NatWest money laundering court case which finished recently. The court heard that one branch of the bank received £42m in cash in 15 months, nearly £3m a month. This was money laundering on an industrial scale and almost certainly linked to organised crime. 

Amazingly no-one at NatWest was found individually culpable for the failures but the bank did co-operate with the regulator and admitted its guilt.

Astonishingly another bank, HSBC, was also fined nearly £64m today for money laundering failures, albeit of a different type. I just hope this is not a trend.

I’m sure like many we’ve all found the money laundering rules irritating. I know many planners I’ve spoken to have found them overly awkward and bureaucratic but they are necessary if we are to stop criminals using financial services as a conduit to launder their ill-gotten gains.

But what of the banks who turned a blind eye? It’s worth remembering that the Money Laundering regulations have been around since 2007 so there has been plenty of time to get used to them.

The problem here is that NatWest appeared to ignore suspicious behaviour that should have set off alarm bells every time. I am assuming here that's it's not normal for NatWest customers to turn up with bin bags full of musty-smelling cash.

There were so many warning signs it is almost unbelievable that no-one at the bank intervened at an early stage and called a halt to what was going on. Many of the notes were either Scottish or musty or both (likely due to being stored under floorboards or in attics / behind walls and so on). Depositing these at a branch in Scotland may have been less conspicuous but branches in suburban London, the west Midlands and Yorkshire were used routinely.

The moral here, if there is one, is that money laundering rules are of no use without vigilant, well trained and alert individuals asking questions and challenging suspicious transactions on a daily basis, supported by their managers. The real failing here was human, not systems.

• This column will be taking a short, but well-earned break until the new year. Thanks for reading the columns this year and for all your Retweets, comments and suggestions. Have a Merry Christmas and good New Year.

Kevin O’Donnell is editor of Financial Planning Today and a journalist with 40 years of experience in finance, business and mainstream news. This topical comment on the Financial Planning news appears most weeks, usually on Fridays but occasionally other days. Follow @FPT_Kevin