The boyfriend of a young mother who was struck and killed by an express train after apparently jumping on to the tracks to retrieve her dropped phone has said he was lucky to have her in his life.

Charlene Pickering, 23, from Walton-on-Thames, Surrey, was hit by the 7.15pm Waterloo to Exeter service at around 7.30pm on Sunday evening after jumping on the tracks to pick up her handset, said British Transport Police.

Investigators described the death as a "tragic accident" following the incident at Wimbledon railway station.

Pickering's boyfriend Daniel Pickett paid tribute to his partner on Facebook.

He posted a message on the social networking site saying: "If only heaven had a phone babygirl I would love to hear your voice just once more.

"I really am not looking forward 2 spending my life without you we had made so many plans and they have been so cruelly taken. I am so lucky to (have) had you in my life even though it was only nearly 4 months."

In his message, Pickett said Pickering was mother to a little boy.

He said: "I will never forget you and Toby was so lucky to have you as a mum and he will be so proud of you and he will also make you proud. Love you beautiful sleep well xx."

Earlier that day he had written a message saying he was going to watch a football watch with Pickering, posting: "(Daniel Pickett) is on the way to Stamford bridge with my gorgeous gf to watch Chelsea vs Pompey."

Andrew Kelly, a councillor from Walton-on-Thames, left a message on micro-blogging site Twitter saying he was at school with Miss Pickering. He said: "Very shocked to hear of the death of an old school friend at Wimbledon Station last night. Far, far too young. RIP."