During this time, he was balancing rugby commitments with study, and graduated from the University of Bath in 2003 with a degree in economics with politics.

A central figure in the absence of many senior players due to the 2003 Rugby World Cup, he set about making his mark on the English Premiership.

[5] Injury prevented him from playing for much of the season – he returned for the Premiership final, but not as captain, as Saracens were defeated by Leicester Tigers.

A regular choice as the England A team captain, from his debut against Wales A at Wrexham in February 2001, he had already played on the full tour of South Africa the previous summer.

[11] A member of England's wider 2003 World Cup squad, he narrowly missed selection to the final 30.

Borthwick initially failed to make England's squad for the 2005 Autumn internationals, with Gloucester forward Alex Brown seemingly poised for a start instead, but injury ruled Brown out of contention and Borthwick stepped in, playing a significant role against Australia, New Zealand and Samoa.

[15] Borthwick came in for a lot of criticism after England's disappointing 2008 Autumn Internationals in which they suffered heavy defeats to New Zealand and South Africa.

This meant he was unavailable for selection against France, so Tom Palmer was bought in as cover and Lewis Moody was given the captaincy.

[18] Borthwick trained as a coach whilst playing with Saracens, taking his initial position at the club's academy from 2012, and also attending the University of Hertfordshire.

On 19 December 2022, it was announced that Borthwick would take over as head coach of the England men's rugby team, replacing Eddie Jones.