[6] He was then sent to England for the King Edward VII Stakes at Royal Ascot but failed to cope with the firm ground and finished unplaced behind Eagle Top.

In September, Dylan Mouth returned to Italy and won the Group Two Premio Federico Tesio, beating Biz The Nurse by three lengths.

On his final appearance of the season he started odds-on favourite for the Group One Gran Premio del Jockey Club over 2400 metres at San Siro on 19 October.

[7] On his debut as a four-year-old, Dylan Mouth started 1/5 favourite for the Group Three Premio Carlo d'Alessio at Capannelle and won by three lengths from Bertinoro.

[8] On his second venture outside Italy, Dylan Mouth was sent to England to contest the King George VI and Queen Elizabeth Stakes at Ascot.

On his first appearance of 2016 he was back in Italy and won the Gran Premio di Milano by five and a half lengths[10] but on his second start of the season was beaten into tenth of eleven runners in the Grand Prix de Saint-Cloud.

On 12 July Dylan Mouth contested the Group 3 John Smith's Silver Cup Stakes over fourteen furlongs at York and went off the 8/1 fourth choice in a five-runner field.

Ridden by Dane O'Neill he came from the back of the field to take the lead a furlong out and held off the challenge of the odds-on favourite Dal Harraild to win by a neck.

At the end of the 2018 season Dylan Mouth was retired to become a National Hunt breeding stallion at the Worsall Grange Stud in North Yorkshire.