Piccadilly line problem due to engineering work at Leicester Square

I travelled to Brighton today, and as the District Line was closed I had to take the Central Line to Holborn and then a Piccadilly line to Green Park for the Victoria line.

The journey from Holborn to Green Park was appalling. The train was delayed, despite assurances that there was a good service on all London Underground lines, and once I got on the train a six minute journey took twenty minutes. The Piccadilly Line is usually fast.

That was at 8:20 am. Transport for London now informs me that minor delays are occurring due to earlier emergency engineering work at Leicester Square.

It would be nice to have been informed about this by Tfl staff and by the overhead announcements instead of being told by "the control room at Holborn" that the line was okay.

I wonder what the emergency engineering work was required for. Was there a problem with the track?

Generally I find that the Central, Piccadilly and Victoria lines are the fastest. The District, Metropolitan and Hammersmith and City lines are the slowest.