The reality TV star - who launched Lucy Mecklenburgh Jewellery today (November 20) - suggested that her former co-star, who she's fallen out with before, would not be able to handle a return to the series.
"To put it bluntly, no, there's no place for her on the show," she said of Childs. "I don't think she could do it.
"She left after series two and we're on series eight now. A lot's changed and we're a lot bigger cast.
"She's been in the celebrity world for so long now. I know we have too, but we're quite down-to-earth and in our little TOWIE community.
"If she came back, I don't think she'd be able to handle it, if I'm honest."
The fashion boutique owner continued: "I'm fine with her now and I don't want to argue with her. I like Amy and our shops are down the same road so I don't want any rivalry there. If I see her, I'll say hello."
Mecklenburgh said of her fellow Essex co-stars, who are endorsing lots of different fashion, jewellery and beauty products: "A lot of us have bought things out, but I've made sure my range is amazing.
"I won't just put my name to things - like some of the TOWIE girls have. I've designed all this myself and the website is mine."
On whether there is room for more Essex jewellery on the already saturated market, she continued: "There was a massive gap in the market for affordable, blingy jewellery.
"No-one's done jewellery well. Amy has tried to do jewellery... I saw her range online. It's nothing like mine at all.
"I have a lot of things like her jewellery in my shop already now - so I've seen it all before."
Asked if she will be providing any vajazzling jewels, she insisted: "No vajazzling! There are none of them in my collection!"
About her own now defunct engagement ring, she admitted: "It's at home but it's going soon. I'm selling it and putting it towards a house.
"We're putting £2,000 of it towards Hamleys for presents for kids at Great Ormond Street Hospital for Christmas, then the rest is going towards a house."
As a 24/7 preened Essex girl, does she ever want to slob around without her lashes and lip gloss?
"I'm normally quite natural. At my shop girls come in and say, 'Oh, are you Lucy?!' because they don't recognise me.
"I've actually toned down quite a lot on TOWIE recently with my hair and make-up more. Although today's look took about two hours!"
The 21-year-old recently called off her engagement to co-star Mario Falcone - after numerous cheating claims - and told us: "I'm so young. It was bit too early. We'll definitely get engaged one day but just not yet."
And is Falcone being a good boy?
"Yes, he is. We had a fun weekend in Paris last weekend. If he'd have proposed up the Eiffel Tower I would have said no anyway."
But it's not all fun, games and glamour for Mecklenburgh, who has been targeted by catty girls on Twitter about lothario Falcone.
"I think girls are always going to be like that," she said. "It really upsets me how vicious girls can be, but what can you do?"
It's no secret she was never best friends with former TOWIE girl Lauren Goodger - so will she be voting for her on the upcoming series of Dancing on Ice?
"It depends on how good she is! I don't see her as a natural ice-skater though. I know I'm no good, but I don't think she'll be a natural.
"We weren't friends before TOWIE and we're not friends now. We're civil when we see each other but I'm not mates with her."
We ask her whether she thinks Goodger is over (her and Mecklenburgh's) ex Mark Wright. She said thoughtfully: "It's been a long time now. I haven't seen any pictures of her dating or anything.
"I think she needs to go out on a few dates, enjoy herself and look for someone new."
And on ex Wright - who hosts Take Me Out: The Gossip - she said: "There's no rivalry between Mark and Mario anymore. They're two completely different people.
"We saw Mark last week at an ITV2 dinner and it was all fine. He came over and said hello to Mario.
"I love Take Me Out, but I don't watch his show - not for any particular reason though!"
Lucy Mecklenburgh Jewellery is available online and is launched by jewellery retailer DiamondGeezer.com