In 2015, McAslan became the British indoor 400 m champion. She ran the anchor leg for Great Britain in the women's 4 × 400 m relay at the 2015 European U23 Championships. The team consisting of Seren Bundy-Davies, Zoey Clark, Victoria Ohuruogu and McAslan won the gold medal in a national U23 record. McAslan also anchored the British 4 × 400 m quartet that won the silver medal at the 2015 European Athletics Indoor Championships in Prague.