London developer Great Portland Estates is planning to deliver its largest ever pipeline of work with spending on schemes set to top £500m.

In half year trading results, the developer said it had now started nine projects amounting to 853,200 sq ft, or a quarter of its total property assets.

GPE also plans to start two West End schemes in the next 24 months at Oxford House, W1 for Facebook and a 224,000 sq ft Crossrail over-station scheme at Hanover Square, W1.

Beyond that, its pipeline includes a further dozen projects, taking the total development programme to 2.5m sq ft. This could take planned investment on building to £513m.

In the last six months GPE has committed to delivering 148 Old Street, EC1,  a major refurbishment of a 97,800 sq ft former Post Office building to create around 156,900 sq ft of offices. Strip out of the building has commenced  for completion in September 2017.

148 Old Street will be stripped back to its structural frame and fitted with new facades of glazed white and engineering brick.

In September, GPE received planning permission at Tasman House, 59/63 Wells Street, W1, to replace a tired 1950′s building with 37,300 sq ft of new office and retail space. The strip out of the building is complete and demolition has commenced with the scheme due for completion in October 2017.

The developer’s committed programme also includes: 90/92 Great Portland Street, W1, which contains the offsite residential offset for Hanover Square, W1;  84/86 Great Portland Street, W1; a 23,100 sq ft mixed-use scheme which contains the offsite residential offset for Tasman House, W1; and 48/50 Broadwick Street, W1, the residential offset for 73/89 Oxford Street, W1.