In Belgrade for the first World Cup of the 2012 season, Marcus raced in the men's quad with Matthew Wells, Stephen Rowbotham and Charles Cousins. After narrowly missing out in a place in the "A final", the crew won the "B final", finishing 7th overall.

At the 2011 World Rowing Championships in Bled, Slovenia, Marcus raced in the men's double scull with Matthew Wells, finishing 6th.

During the 2011 World Cup Series, Marcus with crewmate Matt Wells raced in the men's double scull, winning silver in Munich, 0.05 of a second behind Germany, and bronze in Lucerne.

At the 2011 GB Rowing Team Senior Trials held on 16-17 April at Eton/Dorney, Marcus finished 6th in the men's single scull.

At the 2010 World Rowing Championships on New Zealand's Lake Karapiro, Marcus and crewmate Matt Wells won silver in the  men's double scull.  They had led the race at 500m and then at 1000m and 1500m but in the last 250m New Zealand, roared on by their home crowd, overhauled them to take gold, with France in third.

For the 2010 World Cup Series Marcus teamed up with Matt Wells to race the men's double scull, winning gold in Bled and Munich and silver in Lucerne.  This new partnership worked very well and earned the nickname 'The Red Express' due to both rowers having red hair. 

Marcus dabbled in rowing in 2004 whilst on placement at Lehigh University in the USA.  He learnt to row seriously at the University of Bath as part of the GB Rowing Team's Start Programme, sponsored by Siemens, where he was coached by Paul Stannard.  He won gold in the BUSA Championships and silver in the National Championships in 2005.  Marcus became the first rower from the University of Bath to earn a GB senior vest, and he was invited to join the senior men's national squad shortly after graduating in 2005 with a BSc in Sports Technology.

Marcus gained his first GB vest at the 2006 World Championships where he finished 5th in the coxed four.  He won gold in the eight at the World Cup in Amsterdam in June 2007 and was 4th in the coxed four at the 2007 World Championships in Munich.

Following an impressive 2009 World Cup series which saw Marcus securing two silvers in the quad, in Banyoles and Lucerne, and a 4th place in Munich, he was selected in this class for the World Championships in Poznan.  The boat had a good chance of contending for a final place at the Worlds but bad luck struck when half of the crew had to withdraw through illness or injury.  A real shame.

A former 800m and cross–country schools champion for South Devon, he holds the Torbay AC 800m record and was a Devon Schools' Football finalist.  He enjoys extreme sports such as surfing, kite surfing and snowboarding and his sporting heroes are Seb Coe, Michael Johnson and Daley Thompson.

Marcus is Lottery Funded through UK Sport.