I'm finding that if I'm out all day that my phone is starting to run out by the end of the day and has on occasion gone dead before I get home.

Any recommendations for decent portable chargers that can at least extend the chanrge till I can get home in the evening?

I would FIRST check if you can get a new battery fitted totally free of charge by a local Apple store!

https://www.apple.com/uk/support/iphone5-battery/

I did and it made a significant improvement!

I use one of these:-

http://www.amazon.co.uk/Ultra-Compac...=anker+charger

Nah, checked my serial number and it's not covered.
Got my phone in August 2013 so thought it would be outside the time range anyway.

The battery doesn't run down quickly, it's just when I'm out I use it so much that it goes down anyway.

I'm thinking more of when we go to football and get the train. Great if we get a seat with a power point but a lot of the time we don't. I've found that by the time we're on our way back in the evening my phone is almost dead and won't last the train journey back. Car journeys are easier because I just charge from the cigarette lighter.

Looks good.
How many charges do you get out of it?

Also I assume if my phone is almost dead I can just plug it in and use it whilst plugged into the charger just the same as if I was plugged into a wall?

I've got an Intempo one. Get 70 odd% of an iPhone 5s charge out of it. I got it from an offer in the Daily Mail, but there are some like it on eBay.

Yes, I get two charges (from 20% to 100%) out of it, plus a partial one.

It takes a while to charge itself up, (best done overnight)

And yes, can use the same way, as you would a mains charger.