Pictured: Mother-of-four, 35, who is charged with death by dangerous driving after her son, ten, and daughter, four died in crash with lorry on 'way back from child's birthday party'

A mother charged over the deaths of her young son and daughter in a horror crash on the M1 has been pictured for the first time.

Mary McCann is charged with two counts of death by dangerous driving after her son, Smaller, 10, and daughter, Lilly, four, were killed in a crash with a lorry near Milton Keynes on Monday night.

The children's aunt, Margaret McCann, 26, said the family were on the way back from a party in London when the horror crash occurred. 

Margaret said Mary, 35, of Bamford Avenue, Derby, is a mother of four.  

Her other daughter Marina McCann, 13, was not in the car as she stayed in London with her relatives while Elegance, two, was strapped in a car seat in the car and survived the crash.

She added: 'We are absolutely broken. The kids were like our own children, we raised them together with Mary and we were all so close.

'My son Jimmy is so upset, the cousins were all the best of friends, how am I ever going to explain it to him?'

Mary McCann has been remanded in custody to appear at Crown Court on September 6. 

Mary McCann is charged with two counts of death by dangerous driving after her son, Smaller, 10, and daughter, Lilly, four, were killed in a crash with a lorry near Milton Keynes on Monday night

Devastated family members paid heartbreaking tributes to the children (left, Smaller, right, Lilly) on social media

Their mother's Facebook page showed an image of smaller next to a birthday cake and 10th birthday balloon from earlier on Monday

There was also a post of a birthday cake showing it was Smaller's 10th birthday on the day he died

Smaller and Lilly were passengers in a white Vauxhall Astra which collided with a Scania lorry between junctions 14 and 15 of the motorway, near Milton Keynes

Smaller and Lilly were passengers in a white Vauxhall Astra which collided with a Scania lorry between junctions 14 and 15 of the motorway, near Milton Keynes.

The HGV driver was not injured in the incident, which happened at about 11.10pm on Monday. 

Investigating officer Sergeant Dominic Mahon, of the serious collision investigation unit at Bicester, Oxfordshire, said: 'My thoughts remain with the family of the two children who sadly died at this extremely difficult time.

'We are appealing for anyone who may have witnessed this collision or anyone who may have dashcam footage that may have captured what happened, or either of the vehicles prior to the collision, to please get in touch.'

Devastated family members paid heartbreaking tributes to the children on social media.

One wrote: 'Life is cruel to take them away from my lovely brother. Best old father in the world, he put them first no matter how hard he hit they were his life please god give him the strength.'

The HGV driver was not injured in the incident, which happened at about 11.10pm on Monday (file photo)

The children's aunt said: 'RIP my perfect little niece and nephew. Aunt Elizabeth's old pet Smaller and me little frilly Lilly.

'Love you always and forever and never in this lifetime will you ever be forgotten, always loved.'

A family friend put: 'Mortal divine RIP beautiful angels. So sorry for your loss, their poor mommy and daddy.'

A cousin wrote: 'Can't believe I'm even writing this but rest in peace to my two beautiful little cousins Smaller and Lilly.

'I love you with all my heart. I love you so much this don't even feel real. What has this world come to, hearts in bits. RIP my babies.'