They met at junior school and became firm friends at secondary where they shared a love of canoeing.
Their lifelong bond continued into adulthood. They started their Marconi apprenticeships together and have worked side-by-side for the past 10 years.
Each was the best man at the other’s wedding and they are godfathers to their respective children.
Now Alan Neilson is dying and his best mate, Simon Tier, is having to watch.
The 44-year-olds formed their friendship in the classrooms of Springfield School at Drayton, Portsmouth, when they were 12.
It has remained rock solid through the trials and tribulations of their teenage years, careers, marriage and family life.
But in May last year Alan was diagnosed with an inoperable brain tumour and given two years to live.
It has forced the two even closer and has spurred Simon on to tackle one of Britain’s toughest charity bike rides.
On Sunday he will set off from Land’s End before, hopefully, reaching John O’Groats 12 days and 1,021 miles later.
His aim was to raise £2,740. That’s the figure needed every day to run the UK’s first dedicated brain tumour research centre at the University of Portsmouth.
And it’s that centre which might be giving Alan, of Uplands Road, Drayton, a better quality of life.
Alan and Simon both work for satellite builders Astrium. Alan is a test engineer, Simon a project manager delivering flight black boxes for the space industry.
It was last spring when Alan first noticed something was wrong. Quite how wrong he had no idea.
‘I was doing some gardening and noticed a tingling down one side,’ he says.
‘I went to the doctor, who said he didn’t think it was anything major. He thought it might be a bit of a nerve problem somewhere.
‘The next day I woke up and I was having fits. My leg was kicking everywhere. It was a little bit scary,’ he adds with considerable understatement.
He continues: ‘I went to the hospital, but they didn’t believe me and sent me home at lunchtime. My wife picked me up and as soon as we walked through the front door it started again.
‘She took me straight back and told them I was not leaving until they sorted me out. That was when they did an MRI scan and discovered the brain tumour.
‘It’s the last thing you ever want to hear. I was given two years to live and I’m well into my second year now.’
Soon afterwards Alan accidentally caught a Radio 4 documentary about brain tumours and research being carried out by Professor Geoff Pilkington at the University of Portsmouth.
‘He has discovered that some very old anti-depressants have anti-cancer properties and can, possibly, extend the life of people with brain tumours.
‘After I heard the programme I got in touch with him. He said I’d be ideal for the programme, so now I’m on 40-year-old anti-depressants which are out of licence.
‘I’ve no idea if it’s working for me, but what have I got to lose? The problem is that it’s easy to get people with brain tumours to volunteer for the programme, but, of course, no one with a tumour is going to volunteer not to try it as part of a control group.’
It was Alan’s contact with Prof Pilkington’s centre that raised his and Simon’s awareness of the acute lack of funds filtering into the body which funds it – Brain Tumour Research.
Simon says: ‘Normal cancer treatments aren’t effective on brain tumours. They’ve got to find something different to tackle them.
‘The brutal reality is that survival rates haven’t moved on in the past 30 or 40 years, unlike those of breast and cervical cancer. This is compounded by the fact that only 0.7 per cent of national cancer research funding goes toward finding a breakthrough for the biggest cancer killer of the under-40s.’
Simon went on a fact-finding mission to the Portsmouth research centre where he discovered the magic figure of £2,740 needed every day to keep work going.
Three friends of his had decided to do the Land’s End/John O’Groats (LEJOG) ride for other charities and asked him if he’d like to take part.
‘I jumped at it and knew immediately who I’d do it for – Brain Tumour Research – because of what Alan’s going through and because it’s in Portsmouth.’
Determined every penny raised through sponsorship would go to the charity, the four persuaded IT company Innovise, which has a Southampton office, to cover their travelling and hotel expenses for the 12-day marathon.
Simon’s completed several endurance charity rides on his off-road bike, but he needed an ultra-light carbon bike for LEJOG and that’s where Pippa comes in.
Pippa is the name of the bike. ‘Let’s just say it references my small obsession around the time of the royal wedding last year.
‘I just put a tweet out there telling people what I was doing and that I needed a name for the bike. The first person to reply, who knows me well, suggested Pippa.
‘It really helps when I’m using social media and blogging about the ride and trying to get the message out there, when I personalise it by talking about Pippa.’
Alan laughs. He laughs a lot.
‘I think he’s mad,’ he says of his best friend.
‘But I think what he’s doing is outstanding and people have been so generous.’
The bike ride has been made charity-of-the-quarter by Astrium’s employee charity committee.
Alan says: ‘You do develop a black sense of humour. You have to. There are times when it’s the only thing that keeps you going.
‘Brain tumours are the biggest cancer killer of people under 40 including leukaemia, breast and cervical. Of all the cancers you know about, the one I’ve got is the most deadly. But, for now, my life goes on. It has to.
‘Of course, I went through the ‘‘why me?’’ stage and then someone said ‘‘why not you – you wouldn’t be saying that if you’d won the lottery would you?’’ and it’s perfectly true.’