All at Chelsea send our heartfelt condolences to John’s wife Trish and all his family and friends at this difficult time.

There is a small touch of irony about Dempsey’s most iconic moment in a Chelsea shirt. The tall, no-nonsense defender who was so good at stopping other players scoring was the man who, when the ball fell his way during a finely balanced European final against Real Madrid, executed one of the crispest volleys seen from a Chelsea player to set his side on the way to glory.

That goal was in the 1971 European Cup Winners’ Cup final replay. London-born Dempsey had been signed two-and-a-half years earlier from Fulham by manager Dave Sexton, who had coached him at our then-Second Division neighbours and was by then in his first full season in charge at Stamford Bridge.

Brought up in Kilburn, young aspiring footballer Dempsey had been taken by his father to watch Chelsea and Fulham on alternate weekends. He had even been in the crowd when the Blues won the league for the first time in 1955.

The new addition was to add more steel to Chelsea’s flamboyant squad. Another defender who went on to be a cup final hero, David Webb, had been drafted in a year earlier as Sexton turned an impressive but underachieving team inherited from Tommy Docherty into trophy winners.

Already a Republic of Ireland international (he would earn 19 caps in all) and signed for a sizeable £70,000 fee, Dempsey quickly went into the side on the first day of February 1969, allowing Webb to move to full-back, and there he stayed for the rest of the league season, even if his debut was an ignominious 5-0 reverse at Southampton.

That visit to the Dell was amidst an FA Cup saga against Preston and injury had robbed Sexton of five regulars. Seventeen-year-old Alan Hudson joined Dempsey in making his Chelsea bow that day.

After that shaky start, it was a solid end to season with the Blues finishing fifth. The following year came silverware.

Only two players made more appearances than Dempsey in the long and historic 1969/70 campaign. While in the league, third was our best placing since the 1954/55 championship win, it was in the FA Cup that the greatest height was reached.

Dempsey was a fixture in the no.5 shirt all along the road to Wembley, and then railway track to Old Trafford. He headed in a free-kick to put the Blues ahead in the fifth round at Crystal Palace, one of seven goals overall in the 207 Chelsea games he played.

Another headed goal that season came against champions-elect Everton. Dempsey’s height made him formidable in the air at both ends of the pitch. In defence that aerial prowess was vital in an age of big, physically robust centre-forwards. Arms and legs would be flailing as Dempsey matched them in combat, as would his distinctively long comb-over hair as he also battled to keep up with the fashions of the day.

No side challenged Chelsea more in the physical side of the game than Leeds United, but Dempsey and his colleagues gave as good as they got in the 1970 FA Cup final on the bumpy Wembley turf, and then in Manchester in the replayed game, to bring home that trophy for the first time.

The Blues back-four defence of Dempsey, Webb, Ron Harris and Eddie McCreadie was considered the most solid the club had fielded up to that point.

‘We had the four assassins at the back,’ was a description from their team-mate Peter Osgood, who added mischievously: ‘They couldn’t play football but they couldn't half kick. They hurt people and they really enjoyed doing it!’

Many of the FA Cup team, Dempsey included, made history again a year later by capturing the club’s first European honour. They came within a whisker of beating Real Madrid in 90 minutes in the Cup Winners’ Cup final in the Piraeus port district of Athens but were thwarted by a late equaliser. What that did do however was set the stage for the net-buster from an unlikely source in the replay two days later.

‘It was a corner taken by Charlie Cooke and the goalkeeper punched it,’ Dempsey recalled of his most famous and most significant goal. ‘It was about 12 to 15 yards out and I hit in on the volley and nine times out of 10 it would have gone anywhere, but thank god it went into the roof of the net and it was a fantastic feeling. The groundsman said to me it was the best goal he had ever seen on that pitch.’

Osgood, who went on to score the second goal in a 2-1 win, admitted the rest of the team could not believe it when they looked round and saw it was ‘Demps’ who had rocketed in the opener.

Another cup final appearance came Dempsey’s way the following season but on this occasion the League Cup ended up in the hands of Stoke City.

That was the last season he was an absolute mainstay of the team as turbulent times for Chelsea set in. He missed one entire year due to injury but did lend his experience to the side during the formation of Eddie McCreadie’s young and ultimately promotion-bound side before, following a couple of seasons in the reserves, leaving Chelsea after nine years.

He moved to America and Philadelphia Fury in March 1978 where he was reunited with Osgood and was voted the NASL’s Defender of the Year ahead of Franz Beckenbauer.

In a big departure from football in later life, Dempsey worked as a carer in a centre for people with learning difficulties, on the northern fringes of London. He was a regular at gatherings of former Chelsea players at Stamford Bridge where his warm and generous personality shone through.