Jon, signed initially on a month's loan from Fulham, says of his debut:
"I think we had the first half and they had the second half; it was a good game to watch but it was unfortunate we didn't get the three points.
"In the first half we were unbelievable and we were just passing it around for fun."
Jon was impressed with the quality he saw around him on his debut, and insists:
"I think where we are is not a true reflection of the quality in the squad - we should be right up there.
"I think especially from our first half performance when we dominated the game that we should be playing in the Premiership - but it is important to keep playing like that for 90 minutes."
Jon was at Sheffield United earlier in the season, and he says:
"It was a tough one going back up there; I have had some good times at Sheffield United as well, but as it is we need some points to get up the table.
"They started off liking me but I think they changed towards the end on Saturday - but I have got some good memories of playing there."
Neil Warnock was reportedly unhappy when he saw Jon's name on the team sheet before the game, believing, it seems, that there was a tacit agreement for him not to play against the Blades.
Whether he intended making a permanent bid for him was not explained by the Sheffield United manager, who brought in another left back, Alan Wright, on a permanent basis after a loan from Middlesbrough - though he did not start at the weekend.
But even though the move was not trumpeted ahead of the game - deliberately - Jon's arrival at Upton Park should not have been a surprise to Warnock, as Jon reveals:
"I speak a lot to all the Sheffield United boys anyway, so they all knew straight away - so he would have known."
As for whether the deal becomes permanent, he says:
"I have just been told that I can leave if a club comes in for me; at the moment I am playing on a month's loan and seeing what happens.
"As to anything more than that I haven't got a clue what is going on; I will take one game at a time, do as well as I can, and just take it from there."
As for his spectacular strike that cheesed Warnock off even more, he adds:
"It was just one of those things that happens and I am just fortunate that it happened on my debut - I was well chuffed with it but it just a shame we didn't win.
"I had a feeling it was heading towards the goal but it was swerving a bit so I wasn't certain until the last second.
"It won't be easy to follow that but I am just disappointed we didn't win."
As for the second Sheffield goal, when Anton Ferdinand was not only fouled but lying prostrate in the penalty area injured when they scored, Jon is circumspect.
"Things like that happen and you get goals like that - some go for you and some go against you and you can't argue too much about it," he says.
And the third?
"I was right on the line and it was coming right at me but I was blinded until the last second and I was gutted about that - but it happens and there wasn't more I could do."
Jon arrived on loan with another Fulham player, Andy Melville, and he says:
"Andy is a player who has loads of experience and reads the game well - he is a class footballer and will prove good for West Ham.
"He is getting on but he has experience and has almost got better as he has got older; he knows he is not the fastest in the world but he doesn't need to be because he reads the game so well.
"He will definitely prove to be a good acquisition."
Which is exactly what Alan Pardew, looking to continue bringing players in, hopes about the Fulham pair.
Explaining his transfer policy, he says:
"We have to have one eye on division one next year, one eye on our wage bill which is higher than anyone else's, and got to look to try and get promoted which is our immediate goal.
"It is very crucial that the players I sign permanently are good enough for this club - and there were five loans out there on Saturday.
"I cannot afford to make one mistake and the financial climate means we have lost Ian Pearce, subject to medical, and David James.
"We have got a good replacement in Andy Melville with good composure and experience who has got good motivational skills and we have Jon Harley in with a view to becoming a West Ham player - and he couldn't have done better on Saturday with a fantastic goal.
"Melville, we feel, will become permanent if Pearce's medical comes through and it will be a good deal for us.
"We have to look at the wage bill as well and Ian had a three year contract with us; but contracts were being given assuming we would be in the Premier League for the next three or four years, and we aren't.
"I need some revenue because we have shown all year that we are not good enough because we have not been in the top two.
"I could not sit on my hands and I never will like losing; I have lost enough games at Upton Park to last me a lifetime already.
"What do I do? I have to take educated gambles to turn this club around and in terms of that back five four of them didn't play the week before - it was a risk to take and we nearly got a fantastic result."
But, despite rumours of a Wolves move for David Connolly, Alan says:
"David Connolly won't be going anywhere - he was terrific on Saturday."
Alan is working round the clock to get things right and he adds:
"I haven't played golf or tennis since I have been here and I have hardly seen the kids - but I won't stop until I turn it round.
"I must have done more hours than any manager recently and I don't think anyone would begrudge me that comment.
"I hope to see some players come in this week because I want to give the West Ham fans a bit of a boost.
"They have taken it on the chin and they won't take it on the chin forever - but the critical thing is, if the players we get in help us get promoted are they going to be any good to us in the Premiership?
"I believe that Marlon Harewood and Hayden Mullins for instance are at an age where they can improve could perhaps be Premiership players for us as well as getting us out of this division - and that is the sort of player I am after."
As well as freshening up the squad, Alan is looking forward to the eventual return of Jermain Defoe from suspension and he adds:
"I would have said that I would be disappointed if you had told me we would be ninth at this stage but then again I haven't had Defoe for half the games - which has been an issue, because he is our special talent.
"We are not too different from the top eight but when we have got Defoe in our side we are, and we haven't had enough of him; at some point we need to get a run of games from him.
"He is a top, top player; I have played with Ian Wright and I think he is better than Ian - though Ian won't thank me for saying that.
"He is a special talent and I want to keep him, of course I do; nothing would have given me greater pleasure than seeing him in my team on Saturday - and if he had been in it we would have won that game, no mistake about that."
Alan is desperate to get out of the first division at the first attempt, whether automatically or through the playoffs, and he adds:
"The simple answer is promotion is success and anything else would be a failure to me personally - that is what I want to achieve and what I have come here to do.
"The issues that go around the club in terms of speculation from the press about players and money and not doing well at home are all powerful issues which need to be addressed - and that is what we are trying to do."
Of the game on Saturday overall, Alan says:
"It was a terrific first half and we approached the game in the right manner; when you come to Sheffield United you have got to expect that they are going to put you under pressure and we could have dealt with it better than that.
"We were really unfortunate with the second goal; Anton Ferdinand made an honest challenge, was impeded, and they get a goal from his area.
"We had chances to wrap it up on the break which we should have taken, so were disappointed - but you couldn't fault the effort or the way we approached the game.
"I thought we played some fantastic football and we were that close to getting an away win."
And, of Steve Bywater's first game under him, Alan adds:
"It was tough environment for him to come into, bless him, and we knew he was going to be put under pressure with a lot of balls into the box.
"It was on the TV and David James had just gone in a high profile transfer.
"I thought he did very well with a fantastic save from the penalty; he is disappointed with the last goal - but he can hold his head up high."