Where can four friends meet up in central London?

How about the Crown & Anchor pub near Euston Station or the King's Head pub near Earl's Court Station

There is no Hammer. There is a Hammersmith and City.

None of Circle, Metro (not one of them either, there is a Metropolitan) or Hammer go from Euston.

The Circle Line, the Metropolitan Line, and the Hammersmith and City Lines are served by the Euston Square station, some distance from Euston station.

Euston Station is served by the Northern Line Bank Branch, the Victoria Line, and the Northern Line Charing Cross Branch. Note that for several more months there are no escalators from Euston Station to the southbound Tube lines, only the northbound ones.

Earls Court is not served by the Circle Line. Near but not served.

Note that it is not considered good form to abbreviate place or station, or in this case Tube, names in London. There are too many that are similar, and in transportation it is worthwhile to be accurate. If some place has a name and then a road designation, include the road designation. Don't say Green, for example. Say Green Park, Green Lane, Green Road, Green Park Mews, etc. You will find your life much easier.

Now that that is out of the way, where in South London. If you share that, the answer can be much more helpful. For example, for East Croydon meet under the clock at Victoria Station. For Southwick, meet at the raclette stand at Borough Market, etc.

A very good catch all that may well work is a couple of minutes from the Blackfriars station of the Circle Line and District Line and the Blackfriars station of the First Capital Connect / Thameslink trains.

I suggest meeting at The Blackfriar pub which is nice and has really neat interior tiling.

From Earl's Court, District Line to Blackfriars and upstairs it is right there.

From Euston Station, northbound Victoria Line to Kings Cross St Pancras, upstairs into St Pancras Station and onto the First Capital Connect / Thameslink. 2 or 3 stations to Blackfriars, walk back towards north of the river (the station is over the Thames) downstairs and you are there.

After the drinkie back up to the Thameslink and it takes you to many places in South London.

Thanks for the very careful and accurate responses! After we meet for drinks about 4 pm, we will make our way to Camberwell Green, where we'll meet more family members, and go out to a nearby Turkish restaurant together. No one will be carrying much if any luggage other than a day pack or two.

The Blackfriar would work out well for that. A short Thameslink journey to Elephant & Castle and then a short bus ride to Denmark Hill for Camberwell Green.

I'm sorry about my differing name references to Thameslink. Up to a week ago it was called First Capital Connect but it has been refranchised to Go-Ahead who appear to want to call it by its rightful name of Thameslink. I just don't know what it will say on the signs until they get the permanent ones up.

Agree with Nigel, the Blackfriar Pub would be the spot. Enjoy.

Thanks very much, all you knowledgeable Londoners!

Black Friar it appears to be. Here's a link for anyone curious....

http://www.pubs.com/listing/black-friar-174-queen-victoria-street-blackfriars-city-of-london-ec4v-4eg/

Nigel is spot-on!
When we went to Elephant and Castle it was a dump, very seedy and sketchy on the verge of being scary.

There is a great coffee shop, Costa Coffee, on the corner of New Bridge St. and Bridewell Place. Two blocks up from the Blackfriar's Metro station which is below Black Friars Pub.

It isn't just women, Emma. I avoid underpasses as much as I possibly can and I'm certainly not of the female persuasion. Except at Blackfriars. I'm fine there.