A 13-year-old boy has visited all but two of the 270 London Underground stations in one day in memory of his older brother.

Alasdair Clift, from Wirral, Merseyside, took on the “tube challenge” to raise money for charity Bloodwise after his brother Adam, 17, died from lymphoma in March, and only just ran out of time to complete the whole network.

He began his journey at Chesham station, at the end of the Metropolitan line in Buckinghamshire, at 5.15am on Monday, and finished at Heathrow Terminal 5 station in west London in the early hours of Tuesday morning, having navigated the entire underground network.

Alasdair, who is said to be “fascinated” by transport, has so far received more than £12,000 in donations on his online fundraising page, far exceeding his original target of £100.

Alasdair, left, who is said to be ‘fascinated’ by transport, with Adam. He had originally aimed to raise £100 for charity Bloodwise. Photograph: PA

After spending nearly 20 hours on the tube with his father, Richard Clift, 50, Alasdair arrived at Heathrow to applause from a welcoming party of relatives, tube staff and police officers shortly before 1am.

He said he felt “tired, but proud and happy” of his achievement and the huge support he had received.

“This has been an ambition of mine for a while. In 2013, my brother was diagnosed with lymphoma and unfortunately after many rounds of treatment, he passed away in March. I’ve done this challenge to hopefully give other people a better chance,” he said.

Richard Clift said the kindness shown by fellow travellers and tube workers had been “phenomenal”.

“We have had a very warm day on the tube and in terms of feeling shown to us. We have had terrific support, with people sticking their heads into the carriages saying how wonderful we are and the Transport for London staff have been right behind us. Alasdair felt like a star,” he said.

The family had been touched by the “random gestures of complete strangers” who donated along the way, Richard Clift said.

Alasdair was allowed to ride in the front cab for the first two journeys of the day and was given a certificate recognising his achievement from Mark Wild, the managing director of London Underground, at Southwark station.

Alasdair is presented with a certificate by the managing director of London Underground, Mark Wild, at Southwark station. Photograph: PA

Speaking earlier, Richard Clift said he and his wife Caroline, 51, had been “overawed” by Alasdair, who singlehandedly arranged the challenge.

“We’re very proud, and very proud of his organisation skills, because Caroline and I have had absolutely nothing to do with it,” he said.

Later on his charity page, Alastair said: “Sorry for the lack of updates on the challenge day, but we managed to do 268/270 stations (we missed Mill Hill East and Heathrow T4 as we were way behind schedule to do those) Blame the Circle line for us not doing 270! But otherwise we have had so many donations, were over 22k! Thank you all so far!”