Ms Lord said: “It is heart breaking. There was no warning. I thought they were just going to dig the back garden.”
Westminster City Council sent a planning enforcement team to find the pub was being demolished – three months after developers CLTX Ltd were denied planning permission to build flats.
Councillor Rita Begum, Maida Vale ward for Labour, said: “It was a shock. I have never seen anything like it in my entire life.
“I went past just the other day and there were people drinking inside the pub – there was no warning whatsoever.
“They were going to confirm it as a listed building on Wednesday. I think the developers found out it was going to be a listed building and that’s why the destroyed it.
“The whole community is in shock. How can they do this without approval?”
Historic England confirmed the site was being considered to be a listed site.
Workers sweeping up debris outside the historic pub (Andre Camara)
Westminster City Council will now be seeking legal advice.
A spokesman said: “Westminster City Council’s Planning Enforcement Team received a report that the Carlton Tavern was in the process of being demolished.
“A Planning Inspector of the Planning Enforcement Team visited the site immediately following receipt of the report and noted at 2.30pm that the building had indeed been substantially demolished with only one side wall remaining.
“The building’s demolition required the city council’s prior approval and as no such approval was sought or obtained, the city council will be seeking legal advice concerning whether any future action is legally possible.
“Pubs play an important role in our local community.”
Planning permission was sought in June 2014 on behalf of CLTX Ltd by Kieran Rafferty, of KR Planning, who describes himself on Twitter as an “independent planning consultant helping people deal with the anchors on society”.
The developers wished to completely destroy the existing building and replace it with a ground-floor pub and four upper floors comprising of ten residential units.
It was denied by a planning sub-committee on January 13 because of the “bulk, height and detailed design the new building would be detrimental to the view from the adjacent Maida Vale Conservation Area”.
The application was launched after CLTX bought the pub last year.
Debris inside the former drinking house (Andre Camara)
A spokesman for Historic England said: “The Carlton Tavern built in 1920-21 for Charrington Co, probably by Frank J Potter, was an early inter-war improved public house, carefully detailed and built of good quality materials, showing the vision of a leading London brewery.
“The site was remarkably well-preserved externally and internally, it displayed the hierarchy of rooms in their fixtures, fittings and decorative treatment and retained all its external signage.
“Few pubs were built at this date and fewer survive unaltered. It also had great historical interest as an improved pub, illustrative of growing concern at raising the reputation of public houses, by providing family facilities and reducing drunkenness.
“We intended to recommend the site for listing at grade II, however this is not confirmation it would have been listed, the Department for Culture Media and Sport is responsible for deciding which sites are designated and at what grade.”