One of the goals coach John Mitchell set before England's Women's Six Nations opener with Italy was to strive towards having the strength in depth required to win the next 13 games.

Why end on an unlucky number? Because game 13 would be September's Rugby World Cup final at Allianz Stadium.

Continuity in their Six Nations opener against Italy in York would have been the safe option as the Red Roses bid for a seventh successive championship.

Instead, Mitchell opted against playing his dazzling back three of Jessica Breach, Abby Dow and Ellie Kildunne, who started every game and scored a combined 18 tries in last year's Grand Slam-winning campaign.

There was also no space for regular scrum-half Natasha Hunt or centre Tatyana Heard, while experienced number eight Alex Matthews sat out because of suspension.

From the win over Canada that secured England's WXV1 title success in October, Mitchell made seven changes and some positional alterations to his starting XV, with the result a comfortable 38-5 victory in front of 8,391 supporters in York.

In the early stages, no drop-off was evident. The Red Roses started in clinical fashion, the returning Claudia MacDonald scoring the bonus-point try inside 30 minutes.

But the second half was more of a struggle for England, who came up against a much-improved Italy and were limited to Emma Sing's try in the closing minutes.

"It's a really good start. We had new combinations and built really good pressure," Mitchell told BBC Sport.

"What let the pressure off was a little bit of [lack of] urgency to the breakdown and then execution was probably the only thing that let us down in terms of building pressure in the second half.

"We wanted to build pressure and we have got started with that, but Italy threw a few punches at us as well and we had to deal with that.

"If we don't get punches, how do you learn to get better? I think we will be better for that. Next week [against Wales] will be a new combination again. We have a bit of work to do on cohesion."

England's fresh-looking back three scored 21 points in York and proved more than able replacements in the first half.

Gloucester-Hartpury wing Mia Venner, 22, was playing her first Red Roses game in five years. She looked a threat from her first touch, with her sharp footwork and lethal speed opening the scoring with a well-deserved try.

Creating a dual playmaker system by shifting Holly Aitchison to inside centre and starting versatile back Helena Rowland at fly-half was another new combination which helped England get an advantage in the wider channels in the first 40 minutes.

Debutant GB Sevens player Jade Shekells brought a physical presence off the bench to bounce off multiple Italian defenders, while replacement scrum-half Flo Robinson, through various snipes, also looked bright on her first cap.

"One of the challenges John's got is giving debuts and giving game time to young players, but trying to create synergy in the side," former England head coach Simon Middleton told BBC Sport.

"There were lots of changes and it's really hard to get cohesion."

Mitchell - Middleton's successor - believes it is likely to be during the middle of the tournament when England will start clicking "connection-wise".

Maggie Alphonsi, a 2014 World Cup winner with England, added: "John's thinking about the end [the World Cup] in mind. He's got to accept that there are going to be errors and there are learnings from it. We also knew that they weren't going to be perfect today.

"The key thing is about making sure they develop that cohesion and build those combinations.

"It's about peaking at the right time. New Zealand have done it several times, they've peaked at the right time for a World Cup and they've had errors along the way."

England, who are chasing a fourth successive Grand Slam, next face Wales at Principality Stadium on Saturday.

With their winning streak now at 21 games, another England victory is expected, especially following Wales' opening-round defeat by Scotland.

Whether Mitchell continues to tinker with his side is less predictable, as he continues to develop his winning-machine in the year that will define his side's success.