Here's what I know so far...
Zone 1
* Cally Pool & Gym - Need information
* Chelsea Sports Centre - This one has one or two shower cubicles, mostly open showers, and one disabled shower with a curtain, all in the same shower section just off the changing area. In fact, you can see into the showers while you change.
* Ironmonger Row Baths - Open and Private showers in the pool area. People also talk about using the spa with just a towel and rinsing off naked in the showers outside the spa facilities. Swimwear is required but apparently not always enforced/checked.
* Oasis Sports Centre - The most famous one! Fully open showers in the pool changing rooms here. Quite cruisey. Loads of nudity. They also have a nice mixed sauna outside that looks over the outdoor pool but it's fully mixed/exposed/swimwear.
* Pancras Square Leisure - Private showers
Zone 1/2
* Britannia Leisure Centre - Need information
* Vauxhall Leisure Centre - Private showers
Zone 2
* Better Gym East Village, Stratford - Five open showers heads and one cubicle. Apparently well used.
* Better Gym Holloway - A very small communal shower area. If full, it would be almost cheek-to-cheek.
* Brixton Recreation Centre - In the pool changing area they have private family showers but there's also a fully open shower room with about 6-8 shower heads in a square. Unfortunately it was full of flies when I went. Quite disgusting. You can choose a locker/bench that looks right into the open showers and enjoy the view while you change if anyone else dares use it. They also have men-only health suite days/times (steam/sauna) but swimwear required and no one flouting the rules when I went.
* Clapham Leisure Centre - Private showers
* Clisshold Leisure Centre - Need information
* Copper Box Arena - Need information
* Hammersmith Fitness & Squash Centre - Men's changing room has a tiny men-only sauna, and the men's shower room has a row of cubicles as well as a wall of open showers. One of the the open shower heads is cold for people coming out of the sauna. There are only two other open shower heads and they are next to each other.
* Flaxman Sports Centre - Open showers
* Herne Hill Lifestyle Centre - Need information
* Highbury Leisure Centre - Need information
* Islington Tennis Centre & Gym - Open showers and a sauna
* John Orwell Sports Centre - Need information
* Kensington Leisure Centre - 5 open showers, plus probably 5 cubicles on the other side of the room. That was on the dry side. Not sure about the wet side as it was closed for refurb.
* Kentish Town Sports Centre - Open showers in the pool changing room.
* King's Hall Leisure Centre - Open showers (reportedly)
* Lillie Road Fitness Centre - Undergoing refurb
* London Fields Lido - Private showers
* Mile End Park Leisure Centre & Stadium - Need information
* Phoenix Fitness Centre and Janet Adegoke Swimming Pool - The sports centre has shower cubicles, but the pool has a nice open shower room just for the lads. It a small square room with about 4 shower heads.
* Poplar Baths Leisure Centre & Gym - Mix of open and private showers in the wet men's change (pool).
* Queensbridge Sports & Community Centre - Need information
* Sobell Leisure Centre - About 4-6 open showers with one additional cubicle shower in men's changing area. Towel hooks on the way in. Gets quite busy in the evenings when 5-a-side footballers are in the changing room.
* St George's Leisure Centre - Open showers, well used in the evenings
* Swiss Cottage Leisure Centre - Open showers in the pool changing area. Open and private showers upstairs in the gym changing room.
* Tiller Leisure Centre - Need information
* Whitechapel Sports Centre - Need information, lists gender segregated saunas
* York Hall Leisure Centre - Some open showers.
Zone 2/3
* Archway Leisure Centre - Open showers in the pool area. Nice big room -- good setup. They also have Men only steam/sauna sessions on Monday and Wednesday.
* London Aquatics Centre - Private showers
Zone 3
* Charlton Lido & Lifestyle Club - Need information
* Gunnersbury Park Sports Hub - Opening soon, need information
* Hendon Leisure Centre - Need information
* Leyton Leisure Centre - Open showers (reportedly)
* Streatham Ice & Leisure Centre - Private showers
* The Greenwich Centre - Need information
* Walthamstow Leisure Centre - Need information
* West Norwood Health & Leisure Centre - Need information
Zone 3/4
* Barnet Copthall Leisure Centre - Need information
* Crystal Palace National Sports Centre | Better - Need information, possibly private showers
* Leytonstone Leisure Centre - Mix of open and cubicles in the men's changing room (dry area). However, no lockers in this area.
Outside TfL Zones 1-3
* Barking Sporthouse & Gym - No information
* Barnet Burnt Oak Leisure Centre - No information
* Better Gym Bexley - No information
* Better Gym Bexleyheath - No information
* Better Gym Harrow - No information
* Better Gym Mitcham - No information
* Better Gym Pinner - No information
* Better Gym Romford - No information
* Better Gym Sidcup - No information
* Better Gym Teddington - No information
* Better Gym Walthamstow Stadium - No information
* Better Gym Woowich - No information
* Botwell Green Sports & Leisure Centre - No information
* Canons Leisure Centre - No information
* Chingford Leisure Centre - No information
* Coldharbour Leisure Centre - No information
* Finchley Lido Leisure Centre - No information
* Gurnell Leisure Centre - No information
* Highgrove Pool & Fitness Centre - The dry change has open and cubicle showers with sauna and steam
* Morden Leisure Centre - No information
* New Addington Leisure & Community Centre - No information
* New Barnet Leisure Centre - No information
* Purley Leisure Centre - No information
* Queensmead Sports Centre - No information
* South Norwood Leisure Centre - Open showers
* Sutton Sports Village - No information
* Thamesmere Leisure Centre - No information
* The Eltham Centre - No information
* The Plumstead Centre - No information
* Thornton Heath Leisure Centre - No information
* Waddon Leisure Centre - No information
* Waltham Forest Feel Good Centre - Open showers
* Waterfront Leisure Centre - No information
* Wembley Leisure Centre - No information
* Wimbledon Leisure Centre & Spa - Private showers for the gym. In the wet changing area (pool) they have 4 showers with sides but open fronts (two pairs facing each other).
No Gym
* Academy Performing Arts
* Ashburton Hall & Park
* Croyden Parks & Pitches
* Croyden Sports Area
* Drapers Field
* Feel Good Too Sport Centre, Leyton
* Ferndal Community Sports Centre
* Finsbury Leisure Centre - Open shower room with approximately 10 shower heads in a square. Only has fitness classes, squash courts, and 5 a side football pitches. Time it right with football matches finishing and some guys may shower.
* Gainsborough Playing Fields
* Hackney Marshes Centre
* Highbury Fields Courts & Pitches
* Holloway School
* Lambeth Parks Sports Facilities
* Mabley Green
* Market Road Football Pitches
* Monks Hill Sports Centre
* Paradise Park Football Pitch
* Peter May Sports Centre
* Ridgeway Park Tennis Hub
* Rosemary Gardens Football Pitch and Tennis Courts
* Sutcliffe Park Sports Centre
* Talacre Community Sports Centre
* Thomas Tallis School
* Tufnell Park Playing Fields
* West Reservoir Centre
* Whittington Park Football Pitch
* William Tyndale School Football Pitch
* Wray Crescent Cricket Pitch