We've always used Purple Parking, they are safe, reliable, & are cheaper than the airport car parks.
However, we'll be going away for nearly a month later this year & the cost is high.
I live near another London airport, & there is a nearby "car park" used for "meet & greet".
It is a field, with no security, run by some dodgy characters.
Here's a list of companies that offer LHR parking at a cheaper cost than Purple.
Bee Parking Heathrow - Park & Ride £112.00
Easy Airport Parking Heathrow - Park & Ride £112.50
Heathrow Park & Ride - Park n Ride T2,T3,T4,T5 £114.00
Express Parking Heathrow - Meet and Greet £115.00
Go Park - Meet and Greet £115.00
Parking Panda - Meet and Greet £117.00
Heathrow 365 Parking - Meet and Greet £118.00
Anyone had any dealings with them, please?