Modern but eccentric wiring would worry the hell out of me.
If you aren't an electrician, do yourself, and your family a favour. Get the tumble drier tested. How are you going to feel if you have the same scenario followed by a FIRE!!
For starters, your insurance company aren't going to be sympathetic if British Gas ( who I am no great fan of) have previously condemned your tumble drier. They must have had a reason for doing so...no? And they will keep a record of their visit. In some cases, reconnecting an appliance that has been condemned by a qualified electrician is an offence, so you need to look at this seriously.
Obviously SOMETHING has overloaded a circuit. Don't risk your life with electrics. Modern appliances are, generally, pretty reliable, but like the recent and frightening saga with a particular brand of dishwasher, fires can and do occur.