Image caption Margin/padding problem

The website: http://www.tennysonsbirthplace.co.uk
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I use Weaver II Pro
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I have a problem with the margin/padding when I add an image to a page.
Example 1 – see Homepage. I added the image and gave it a border, nothing else, no padding, no margins and this is the result.
The code I see when switched to text view (wp 3.5) is this: <img class="alignleft size-full wp-image-650" style="border: 1px solid black;" alt="St Margarets frontaal m pleister" src="http://www.tennysonsbirthplace.co.uk/wp-content/uploads/2012/12/St-Margarets-frontaal-m-pleister.jpg" width="300" height="225" />This website has been… etc.

Then I give edit the image and give it a border , to see how the spaces are divided. Result on the page “St Margarets.”
I can of course change the padding and margins so that it comes as I like it (by adding margin/padding to the code in text-mode, a few px right and bottom but the real problem starts when I give the image a caption, see page Tennyson; the margins are much too wide.
The code in textmode on that page is: [caption id="attachment_650" align="alignleft" width="300"]<img class="size-full wp-image-650 " style="border: 1px solid black; margin: 0px 3px 4px 0px;" alt="St Margarets with a plaster..." src="http://www.tennysonsbirthplace.co.uk/wp-content/uploads/2012/12/St-Margarets-frontaal-m-pleister.jpg" width="300" height="225" /> St Margarets with a plaster...[/caption]The small, secluded hamlet of Somersby…etc.
I can’t find settings for the caption but it seems that the caption causes the trouble.
Hope it is clear enough.