Sitting in Gail's after school drop off, I ordered myself a flat white and an avocado toast and looked forward to having a long, overdue chat with one of my oldest mum friends. Arriving late, she was skittish, with huge pupils and a nose that wouldn't stop running, disappearing to the toilet a few times during the course of our catch up and seeming increasingly lively each time she returned.My friend had always been a party girl and I knew she enjoyed the occasional line of cocaine on a weekend but it was 10am on a Monday when I realised her habit was seriously out of control.Rail thin, 40-something and permanently jumpy, the serious cocaine-using mums are easy to spot in this affluent suburb in the north of England, where decent sized family homes can command £800,000. Some couples we know are lucky enough to have benefitted from generational wealth, others have relocated after selling smaller London pads for sizable sums after starting families and needing more space.The next time I heard from my old pal was in a confusing, late night phone call in which she expressed her anger that the regulars at her favourite wine bar had turned on her. She was making little sense but I eventually gathered she'd been told the dirty looks she was receiving were because someone had spread the rumour she had dropped a bag of the Class A drug on her way out of the toilets.'They've got it out for me,' she raged. 'It's a ridiculous accusation: a bag that size is far too pricey to leave behind.' 'Rail thin, 40-something and permanently jumpy, the serious cocaine-using mums are easy to spot in this affluent suburb in the north of England, where decent sized family homes can command £800,000,' claims the writer (stock photo) I had to distance myself from my former friend, who has three young children, after a few of us tried to stage an intervention that failed miserably. She stopped answering our calls and last I heard, was seen crashing her car into a lamppost on the school run after a heavy night out.And while her behaviour became too obvious to ignore, she isn't the only school mum round here with a major cocaine habit.Back in January, I was delighted to receive a phone call from our local cricket club, saying my eight-year-old son had finally made it off the lengthy waiting list.Giving us a tour, the manager and I got on like a house on fire and when I took my boy back for his first training session later in the week, he gave me a friendly wave from the clubhouse.After the class, I was enjoying a glass of wine with a nursery mum acquaintance as our kids played together after their lesson, when to my surprise the manager who had been so welcoming walked past and gave us a furious glare.'He hates me,' explained the mother, an accountant with whom I'd chatted at many a kid's party. 'It was a huge misunderstanding - I was having a drink with a friend after the lesson and the pal invited another mate along and it turned out he was a drug dealer.'The manager caught the dealer in the cricket club toilets with a huge stash and called the police but he legged it. It was nothing to do with me but I'm being blamed by association.'My acquaintance's insistence that she didn't know the man dealt drugs seemed much less likely when I looked at her more closely. Pencil slim and dressed immaculately in Me+Em jeans and a Zara top, the sides of her nose were red raw underneath the layers of make-up she'd carefully applied.'It's eczema,' she fibbed without me uttering a word, reaching for a tissue in her handbag. 'I just can't get rid of the peeling skin, I'm so embarrassed.'From huge, shiny 4x4s clogging up roads on the school run to cinemas and hot tubs squeezed into the basements of beautiful period properties, signs of wealth aren't hard to find in this lovely suburb.Cocaine costs up to £100 a gram in these parts and while some school mums I know can easily afford as much of the drug as they want, others live well beyond their means when it comes to their heavy habits.'I've added up what she owes me and it's thousands,' a shocked friend who is a hard-working barrister told me, referring to a TV soap producer who has a child in my son's class. 'She'll ring me up in tears and say her bank card isn't working so I'll help her out.'Sometimes she says she can't get her banking app to work to pay me back, on other occasions she'll insist she has transferred the money back when she hasn't. I love her and her children but I can't carry on like this.'I know the money's going straight up her nose but she denies it, she just won't listen to reason.'I've only been asked for £10 here and there from this same pal, probably because I'm significantly less wealthy than our lovely, generous mutual friend.I recently saw the TV producer looking gaunt and jittery at my daughter's tenth birthday party in an inflatable soft play venue, cringing when I overheard a classmate's mother innocently inform her that her nostrils were bleeding.Last summer, my core group of school mums and I headed off for a long weekend in Rome leaving the dads in charge. Returning home after the trip, everything had gone well in my household but other friends weren't quite so lucky.One had suggested her husband get together with two other dads in our circle while we were away, so he invited their families to his house on Sunday afternoon.A short time after the playdate finished, my friend's three-year-old came out of the downstairs toilet with a tiny plastic bag containing a trace of white powder, asking her daddy what it was.My circle of mums has fractured as a result of the fallout, amid a furious debate about which father - the pilot or the advertising executive - left drugs in the downstairs loo on a playdate. Both have furiously denied the accusation but I have my suspicions...