Zara Tindall was pictured for the first time with her five-week-old son Lucas Philip Tindall at the Cirencester Park International Horse Trials on Sunday.

Cutting a low-key figure in a baseball cap, jeans and boots, Her Majesty's granddaughter, 39, barely took her eyes off her baby boy's pram as they enjoyed a day out.

The doting mother appeared to introduce Lucas - who was tucked away in his pram - to other spectators before taking a phone call.

Zara - who shares little Lucas with her husband Mike Tindall - was at the event to support her horse Classicals Euro Star, ridden by equestrian Jason Wood on the day.

She wore her hair swept back into a bun and at one point pulled her rain jacket's hood up around her face to keep the chilly weather at bay.

The royal also stopped by a food van.

Zara received an MBE in 2007 for services to equestrianism and won a silver medal at the 2012 Olympics as a member of the Great Britain Eventing Team.

The mother-of-three gave birth to their son Lucas, weighing 8lbs 4oz, at 6pm on a Sunday in March on the bathroom floor of their family home on Princess Anne's Gloucestershire estate.

Zara and Mike, 42, also have daughters Mia, seven, and Lena, two.

Mike confirmed the news of his family's new arrival on his podcast The Good, The Bad and The Rugby - and hailed Zara a 'warrior'.

Speaking in March, he revealed he took the little one straight downstairs to watch sport on TV, after snipping the cord and enjoying skin-on-skin contact.

The unconventional royal birth announcement via Mike's podcast shows yet again a different approach from the Tindalls, who revealed their third pregnancy in the same manner.

In the past, the couple had pregnancies formally announced by Buckingham Palace.

A spokeswoman for the couple said: 'Zara and Mike Tindall are happy to announce the birth of their third child, Lucas Philip Tindall.' The little boy is the Queen and the late Duke of Edinburgh's 10th great-grandchild, and 22nd in line to the throne.

Speaking about the birth, Mike told how Zara had experienced contractions the night before, so they organised childcare for Mia and Lena - but the little boy arrived so fast they didn't have time to make it to hospital.

Mike recalled: 'Fortunately Zara's friend Dolly [Maude] is, she's actually more important than I am at making sure she's been at all three of my children's births, she was there and recognised that we wouldn't have got to the hospital in time, so it was run into the gym, get a mat, get into the bathroom, towels down, brace brace brace!

'Fortunately the midwife that was going to meet us at the hospital wasn't that far away so she drove up, got there just as we'd assumed the position, and then the second midwife arrived just after the head had arrived!'

Asked how his daughters reacted, Mike admitted they didn't tell them they thought Zara was in labour, but he suspected Mia had sussed.

'Mia's quite on it, she's quite street smart, so she was like, "why are we not going home for tea?" They were going, "they've had to pop out for something..." "where have they had to go?" will you just stop asking questions... and then when she got in she was over the moon, both of them were.

'Problem is Lena is like, "my baby!" And it's like, no Lena, it's not your baby! She tries to pick it up... so yeah.'

In December 2016 the couple revealed that they lost their baby, a month after announcing the pregnancy.

Two years later in an interview with the Sunday Times, Zara, opened up about the devastation of losing the baby and revealed she had suffered a second miscarriage before falling pregnant with daughter Lena, now two.

Zara said the hardest part of her first miscarriage was having to tell the world because news of the pregnancy had been made public.

She explained: 'In our case, it was something that was really rare; it was nature saying, 'This one's not right.' I had to go through having the baby because it was so far along.'