If your computer was stolen or lost in a fire would your digital images be insured under your household contents policy? As they are probably irreplaceable anyway is insuring them actually worthwhile - probably not.
However having just received my renewal quote I was surprised to see one of the amendments to my policy is that digital music, video and photos are now covered to a maximum of £2,500 as standard.

So if if you can't replace the photos you might be able to buy a new lens to help you start over as a bit of a consolation.
I asked on BF who people recommended for insurance about a year ago and got very little response so I did my own research and came up with "Hiscox".
One of the main attractions was that they covered theft from an unattended vehicle to £2.5K were as most companies only cover £1k. In addition "new for old" is standard as is "all risks" and "Worldwide" cover, nor did I have to list higher value items individually. Oh yes - and I saved £200 per annum on what I had been paying to a high street company.
I had to make a claim this summer on the buildings element of the policy and the claims service was friendly, hassle-free and infact superb - including them phoning me the day after I sent the final bill to confim that I would be happy if they made payment by direct transfer in order to get it cleared in my account within 2 days !!
If you fancy checking them out for a comparrison with your own insurer a quote service and full policy details are available
here
PS: I promise I have no link with this company - I'm just a very satisfied customer.