ESPNsoccernet: Soccernet

David Unsworth: His penalty prowess made him a real threat from the back (GettyImages)

As with most things, that depends on how we define a defender. Given his very occasional appearances at right back, Steven Gerrard could qualify, though not for this observer. But Gareth Barry has a case to claim the title after spending much of his early career at either centre back or left back. He has 44 Premier League goals, but as 30 of them came in his final six seasons at Aston Villa, when he operated almost exclusively in midfield, I don't think Barry is the appropriate answer.

So, instead, the accolade passes to another left-footed penalty taker with Villa connections - he was signed for them but never made an appearance - in David Unsworth. He scored 38 Premier League goals - the vast majority for Everton, but with strikes for West Ham, Portsmouth and Wigan completing his quota. Unsworth's only goal for Wigan, incidentally, was the one that kept them up in 2007 and, typically, it came from 12 yards.

He is only one ahead of Bolton's Matt Taylor, though the majority of his 37 goals have come from midfield. To find another out-and-out defender, we have to go down to 28, the number mustered by Ian Harte in his days as Leeds' spot-kick expert.

Among non-penalty takers, the highest placed out-and-out defender is Sami Hyypia, whose 22 Premier League goals place him just outside the top 200 scorers in the division's history. And, among current top-flight players in England, as the top-scoring defender is 36-year-old Sol Campbell (with 20), Unsworth's record should be safe for several years to come. John Terry, with 19, could be a long-term threat, but he would have to score with rather more frequency in the second half of his career to be pass Unsworth.

Have any players scored the winner for their opponent with a trophy on the line? asked Andrew Steevens from Milwaukee, Wisconsin.

They certainly have. Indeed, one player has been involved in two decisive own goals in FA Cup finals in the space of five seasons. Gary Mabbutt, one of Tottenham's greatest servants, had the misfortune to deflect a Lloyd McGrath cross past his own goalkeeper, Ray Clemence, when the scores were level at 2-2 in extra time in the 1987 final. Four years later, Tottenham were drawing 1-1 with Nottingham Forest when Mabbutt went up for a corner. He had a chance to head it in, but his unfortunate marker, Des Walker, got the touch so it was an own goal that earned Tottenham the trophy.

Mabbutt is, incidentally, immortalised in Coventry to this day. A fanzine, which has developed into a website, is called 'Gary Mabbutt's Knee' after the part of his body that won Coventry the only major trophy in their history.

There are plenty of other decisive own goals in football history; Damien Duff's for Newcastle at Aston Villa in 2009 relegated the Magpies and may be costliest financially, although, in another respect, Andres Escobar's own goal against the United States in the 1994 World Cup tragically came at a greater cost.

I was wondering if there has been any match in recent history that has ended without a card been issued? asked Henry McHenry.

There have been quite a few. The most recent in the Premier League occurred earlier at the weekend, Stoke's 3-0 win at West Brom. The previous one also involved Tony Pulis' team, their 3-2 win over Birmingham on November 9. There are four earlier examples in England's top flight this season: Birmingham 0-2 Everton on October 2; West Brom 2-1 Fulham and West Ham 1-2 Newcastle, both on October 23 and, on October 30, Fulham 2-0 Wigan. All of which may suggest that games involving any of Stoke, West Brom, Fulham and Birmingham are the easiest to officiate.

I have an interesting question for you: has there been any season where the gap between second and third place is 20-plus points, since the English league started? And what is the greatest margin if there has never been a 20-plus point difference? asked Vishal Bhartia.

The answer to your first question is simple: no. In the history of the English top flight, which began in 1888, much the biggest gap between second and third place is 15 points. That was comparatively recent, in the 2006-07 season, when it is fair to describe the battle for the title as a two-horse race. Manchester United won it with 89 points, six more than Chelsea. Liverpool were the best of the rest with 68 points, 15 fewer than Chelsea, but the same as Arsenal.

However, there is a different story in other countries. In La Liga last season, Barcelona were the winners with 99 points, three more than Real Madrid managed. Third-placed Valencia came in 25 points behind Real.

Meanwhile, there was a gap of more than 20 points between second and third as recently as 2008-09 in Scotland when Celtic (with 82) were runners-up and Hearts (59) the next highest team. Twice in the past decade, more than 30 points have separated second - and the Old Firm - from the rest, with a remarkable 34-point gap between Celtic (in second) and Hearts (third) in 2002-03.