Beans on toast. Boom. Done.

How about making scotch eggs? I have also seen them called Irish Eggs but I only know them as the former. Basically, hardboiled eggs, wrapped in sausage meat and then fried. You can easily make them ahead of time and then serve them cold, cut into quarters, with some mustard. More recently, I made some with spicy sausage meat and they were delicious. And they are always a hit...and something a bit different! Good luck!

sticky toffee pudding? some kind of curry dish? fish and chips? anything boiled?

When I think of English food I think of meat pies.

Mushy peas and fish fingers, mini yorkshire puddings and roast beef, scones and clotted cream, cucumber sandwiches, homemade jammie dodgers.

Pigs in a blanket (UK style - cocktail sausages wrapped in bacon) and cheesy chips and gravy (fries with a dark beef-based gravy and grated sharp cheddar) are two great snack foods. As the national dish, chicken tikka masala is amazing.

sausage rolls (in flaky puff pastry) are excellent party food and very british. or Cornish pasties.

Pies I miss the most from home are: chicken and mushroom, and beef and onion. Cornish pasties are also delicious. Leek and potato soup, carrot and coriander... Chelsea buns for dessert.

Fish fingers in custard. Boom. Done.

Oh my…

Here's a link to BBC Good Food for inspiration:
http://www.bbcgoodfood.com/content/recipes/cuisines/british/

Otherwise my recommendations are: Toad in the Hole, Chicken Tikka Masala, Curried Beef Mince Pie, fresh side dishes of courgettes and other summer veg, Fish Pie, Cottage Pie, Lamb Stew, all big dishes to feed a crowd.

You should serve Pimm's cups - way more interesting than just ales. I also remember really enjoying "pasties" when I was in the UK. Lovely pastry pockets filled with veggies and sometimes meat. You could make them ahead of time and warm them up when you arrive

You need this. http://www.bbc.co.uk/food/recipes/search?programmes[]=b0071y6r
Banqueting with an olympic theme for this year's season.

http://www.bbcgoodfood.com/recipes/2515/chunky-oven-chips

Here's a good chip recipe too! You'll need tons of these.

Bangers and Mash! I was just there last month and that was my favorite meal. Another great meal would be meat pie as other have stated.

Ooh! British food! Fun!

I have some recipes for vegetarian versions of meat pies that are really nice. You might not be looking for vegetarian food, specifically, but these are really flavorful, and I've always found vegetarian food to be welcome at any party.

I've got quite a few versions of non-sausage rolls. With greens and olives;with roasted mushrooms, white beans, and nuts; or with butternut squash and goat cheese.

Here's a vegetarian version of small meat pies (served with mash & liquor (parsley sauce) in a certain part of London, but nice on their own. Very tasty and almost meaty with black beans, roasted mushrooms, marmite, sage, smoked paprika...

Here's a veggie version of cornish pasties with potatoes, turnips, greens and cheese.

And if you're feeling fancy, I've got two versions of beef wellington. One with portobellos, one with eggplant.

Sorry, I just saw the comment about chicken and mushroom pie and it reminded me of two more...

A deep mushroom pie...almost like a vegetarian pork pie. Delicious!

And a roasted chickpea and mushroom pie, which is more like a chicken and mushroom pie. My friend in England has made this several times!

Eton Mess! Very British, and perfect for a hot summer event...

@Rachele...love it!! If you have anyone who won't be drinking the ales, maybe find some Ribena (a black current flavored drink). I also second Lauralop's suggestions of sausage rolls. For a dessert, a treacle sponge pudding.

We always try to have something appropriately festive for dinner during the opening ceremonies. I'm pregnant and don't feel like cooking much these days, so we settled on Indian take-out! Not totally British, per se, but certainly very popular in London!

http://www.bbcgoodfood.com/content/recipes/cuisines/indian/

Here's link to some Indian recipes too if you're feeling Anglo-Indian for your party.

I second Miss Moshi on Eton Mess. Alternatively, you can't go wrong with the chocolate biscuit cake that Wills had as his groom's cake.
http://www.browneyedbaker.com/2011/04/29/chocolate-biscuit-cake-royal-wedding-groom-cake/

Scones with jam and clotted cream. Egg & cress sandwiches. Mini Yorkshire puddings with roast beef & horseradish cream. Pimms.

Eat like actual Brits. Have Spaghetti Bolognese and garlic bread, wafer thin ham sandwiches, tea and assorted biscuits (cookies).

I'd suggest looking at Felicity Cloake's column in the Guardian. How to cook perfect...

It's not all English, she's done a lot of french and American lately. But it's always a fun read. And you can find ur recipes for sausage rolls (non-veg!) and scotch eggs, and plenty of other things, I'm sure!

http://www.guardian.co.uk/lifeandstyle/wordofmouth/2012/jul/12/how-to-cook-perfect-jerk-chicken

if you are doing ale then a good ploughman's to go with it! wasn't there a link on here somewhere? don't forget the branston pickle!

I worked as a bartender in a national park, and all of the brits would order shandies 1/2 lemon/lime soda half beer, usually a lager. Makes it really light and refreshing on a hot day they claim.

Fish fingers and custard FTW!

Chip buttys (sandwiches made out of buttered bread with hot fried chips (aka French fries) have apparently been banned at the Olympics because McDonald's owns all fried potato rights at the Olympics except for fish and chips. So go anti-MacDo and make chip buttys!

I also second the Pimm's Cup as a perfect summery drink.

Stargazy pie. Just kidding. It's one of the Brits weirder dishes.

My serious suggestions is Eton Mess for dessert. It's easy and delicious.

Cheddar and pineapple cubes on cocktail sticks, displayed on half a grapefruit wrapped in tinfoil. Classy! ;)

Victoria sponge cake? Simple and delicious.

If you do Pimm's make sure you call it "Pimm's and Lemonade" though, nobody says "Pimm's Cup" here. Or if you wanted to get everyone totally pissed, do a Snakebite and Black (half lager, half shandy, with a shot of blackcurrant cordial). Vicious stuff.

As a British person some of the foods/flavours I associate strongly with *traditional* or *classic* British food are rhubarb, elderflowers, strawberries, watercress, salmon (inc. smoked), apples, blackberries, radishes, cucumber/borage, mint, chives...

Trifles and eton mess are good suggestions. See if you can find any Nigel Slater trifle recipes online - he excels at them. Perhaps a layer cake of elderflower-scented sponge sandwiched with lemon curd and strawberries.

In addition to Pimms I would also suggest good dry cider (all cider in Britain is alcoholic) G&Ts and elderflower presse.

A plate of really good British cheeses - Lincolnshire Poacher, Stichelton, Tunworth etc

Also this menu from Northern Irish food writer Diana Henry for the Queen's Jubilee might be useful:
http://www.telegraph.co.uk/foodanddrink/recipes/9246285/Delicious-dishes-for-your-Diamond-Jubilee-street-party.html

Another Brit here, how about tea poached salmon, roast beef and horseradish sandwiches, roast potatoes, strawberries and cream, trifle or bakewell tart. Have a fun party!

i second @vintagejenta's suggestion for chip buttys!! along with pasties, it's my favorite British food.

oh and Marmite and cheese sandwiches!!!

Corollary question: does anybody know if there are names for the various filled Yorkshire puddings? I know about Toad in the Hole, but I'm wondering about the ones that are filled with stews and other savory foods. Google brings me a lot of recipes with "filled yorkshire pud" but I can't believe there isn't a specific name (MIL, who lived in the UK, says they are "Eiffel Trifle," but I see no online evidence of such.)

BTW - feels very British, and is possibly the best way to enjoy a stew.