Mental health patients are being turned away from hospital after South West London and St George's NHS Mental Health Trust (SWLSTG) removed more than 150 beds in the past two years.
Data revealed in a joint investigation by Community Care magazine and BBC News found the trust, which operates from nearly 100 locations has removed 177 beds from 18 wards and closed five.
Figures released by 28 mental health trusts around the country show they are running at an average of more than 100 per cent capacity, well above the recommended 85 per cent level.
SWLSTG failed to answer a Freedom of Information request on occupancy levels, but admitted they have closed 177 beds in the past two years.
An annual report stated the trust had just 430 beds to deal with the 2,500 inpatients admitted in 2012/13.
Seacole ward, in the trust's head quarters Springfield Hospital, Tooting, was one of the worst affected wards with 22 beds removed in 2011.
The adult acute ward, which treats young adults aged up to 23-years-old, now only has eight beds with money being pumped into home treatment instead.
Petersham Lodge, located in Barnes Hospital, Worple Way, Barnes, also had 22 beds closed from 2011 to 2012.
The drugs and alcohol service in Springfield Hospital was decommissioned in 2012 losing 13 beds, as well as rehab centres Burntwood Villas, Earlsfield, and Southbank House, Surbiton.
Secure ward Ellis (Gaskell) closed in 2012, while learning disabilities service The Jasmine's Centre, in Tolworth, closed this year and lost 11 beds
Other reasons for removals include new wards built with less beds to make room for better quality facilities, fewer patients being admitted and moving services to other wards.
Gerry Horner, of Keep Our NHS Public , said: "One observer has told us of seeing patients on an admission ward being transferred to other wards or even to other hospitals, thus disrupting their treatment, in order to make way for new arrivals.
"One new patient admitted under section was observed waiting for hours before a bed, which had been booked, actually became available.
"Such a situation would obviously impair the ability of nurses and doctors to re- assure and welcome new patients."
A spokeswoman from SWLSTG said: "Most of this reduction has been due to reinvestment in Crisis Home and Treatment Teams leading to a reduction in bed use and closure of wards.
"Hospital admission is only used when absolutely necessary. Furthermore, we do not routinely move people into mental health beds outside South West London.
"We do not currently have any out-of-area acute placements for adults or older adults.
"We have briefly utilised privately owned accommodation when wards are being reconfigured and are not intending to use this measure again as we have sufficient space on our wards."